by a solution of the diacetate of lead. If you are afraid of nitrate of silver burning the neighbouring parts, its action may be neutralized by common olive oil. A solution of the bicarbonate of potash will decompose chloride of zinc; and so with other caustics."

Sir B. Brodie does not agree with Dupuytren, who described the gangrene that occurs in old age as the result of arterial inflammation. He has examined the bodies of a great many old persons who have died with mortification of the toes, and has always found some morbid condition of the arteries of the affected limb. In the very great majority of cases there is extensive ossification of the arteries of the thigh and leg; in many cases they are not only ossified, but some of them are contracted and obliterated. This we believe to be the view entertained by all the best English pathologists, whilst the majority of the French adhere to the erroneous views of Dupuytren. It has been said that mortification of the toes in old persons is often the result of disease in the heart itself. This does not correspond with the results of our author's experience. It is true that he has known persons who had disease in the heart to die of mortification of the toes; but then there was always enough in the condition of the arteries of the limb to account for the mortification independently of the other disease. Sir B. Brodie recommends neither depleting nor a decidedly stimulating treatment, but a nutritious diet and such stimulants, suited to the previous habits of the patient, as do not occasion heat of skin nor raise the pulse. He advises the limb to be wrapped in carded wool, and we are not surprised to find that he strongly objects to amputation even when the mortification is arrested. "If you apply your knife to living parts, you will probably bring on a fresh attack of mortification. Leave the separation altogether to the natural process, which will do all that is required."

Lecture XXI., the last in the volume, is on Chronic Abscess of the Tibia. A case is related of extremely painful enlargement of the lower end of the tibia which led to amputation of the limb. A cavity, as large as a small chesnut and containing pus, was discovered in the diseased bone. This occurred in 1824. It was clear that, if an opening in the tibia had been made with a trephine the limb might have been saved. In a case of painful enlargement of the tibia, in which Sir B. Brodie was consulted about two years after the occurrence of the preceding case, he made an opening into the cancellous structure of the bone with a trephine, and having given vent to some pus, the patient became cured. Four other cases, three of enlargement of the lower end of the tibia, and one of the upper, are related. They were all trephined with a successful result in giving exit to pus and curing the patient of a most painful affection. The operation has also been twice successfully performed by Mr. Liston. The following important questions present themselves. What are the circumstances that would lead the surgeon to suspect the existence of abscess in the tibia? And, supposing it to be probable that such an abscess exists, what are the exact steps of the operation to be performed for its relief?

"When the tibia is enlarged from a deposit of bone externally-when there is excessive pain, such as may be supposed to depend on extreme tension, the pain being aggravated at intervals, and these symptoms continue and become still further aggravated, not yielding to medicines, or other treatment that may be had

1846.]

CHRONIC ABSCESS OF THE TIBIA.

21

recourse to, then you may reasonably suspect the existence of abscess in the centre of the bone. You are not to suppose that there is no abscess because the pain is not constant; on the contrary, it very often comes on only at intervals, and in one of the cases which I have related there was, as I then mentioned, an actual intermission of seven or eight months. After the disease has existed a certain number of years, indeed, the pain never entirely subsides, but still it varies, and there are always periods of abatement and of exacerbation. The combination of circumstances which I have described will fully justify you in making an opening into the bone with a trephine. But how will it be if you are mistaken? This will not often occur; but if it should, the taking out a circle of bone can be of no consequence; no injury follows the operation it is unattended with danger. The operation itself is very simple. You expose the surface of the bone, and make a circular opening with a trephine at that part where there seems to be some tenderness and some pain on pressure. One principal thing to be attended to is that you have a proper trephine. You do not want so large a one as for the cranium, and it must be somewhat differently constructed. Those which lie on the table are made for the purpose. One is of very small diameter, but, generally, it is quite sufficient. The common trephine is made with a projecting rim or shoulder, and if there be much enlargement of the bone, it will not penetrate deep enough to reach the abscess. It is true that you may break away the bone afterwards, by means of a chisel, but the operation may be more easily performed with a trephine having no projection, which will at once penetrate to the abscess, however deep it may be, and render the chisel unnecessary." P. 405.

After the operation, the bone soon granulates, the space is filled up by a sort of fibrous substance, and the wound cicatrizes. Sir B. Brodie states that, if the operation were not performed, the patient may continue in torture for a great number of years, losing all the best part of his life; or a worse event than that may take place. The abscess may lead to disease in a neighbouring joint and in this way prove destructive to life. Cases are given in which abscesses in the head of the tibia had caused serious disease of the knee-joint. These cases "show that it is not safe to leave an abscess in the extremity of the tibia beyond a certain time; that the joint is always in danger, and that the perforation of the bone is the only remedy. Even if you were mistaken in your diagnosis, no harm can arise from the operation.

99

A case is mentioned of a young gentleman who had a painful enlargement of the middle of the humerus. It was trephined freely, but no matter escaped. The bone was very hard and compact, and the trephine was with difficulty made to penetrate through it. The wound healed, the relief was complete, and the patient continued quite well. Sir B. Brodie supposes "that this was a case of chronic inflammation of the humerus, and that taking out the piece of bone from the centre, probably, partly by relieving the tension, and partly by a discharge of matter from the bone unloading the vessels, accounted for the relief which the patient obtained from the operation."

Notwithstanding the result of this case, it cannot be questioned that the greatest care and caution are required in determining the necessity for an operation for the evacuation of a supposed abscess in the substance of a bone. We have been informed that, not long since, a limb was amputated by a hospital surgeon, in consequence of a suspected abscess in the head of the tibia of a painful character, and implicating the knee-joint. On

examination of the limb after removal, the joint and tibia were found to be quite healthy, and the complaint proved to be hysterical.

We here terminate our notice of these interesting Lectures. We have not attempted more than to furnish an outline of the subjects treated of, and a condensed account of the more important contents of the volume, giving such extracts as may appear likely to be useful to the majority of our readers. Sir B. Brodie's position in the profession and great experience are such that his practical writings must be considered as beyond the reach of criticism, at least by those of more limited observation. Time will be the best test of the value of the principles inculcated and of the suggestions for the treatment of disease. We strongly recommend our friends not to rest satisfied with this notice, but to read the volume itself, and we can promise them that, by doing so, they will obtain a clearer insight into many obscure subjects of surgical pathology, and become better armed to overcome the difficulties of practice. It now only remains for us to return our most hearty thanks to the author for this valuable contribution to surgical literature, and to express a cordial hope that he may have health and leisure to fulfil the expectations which he has held out of publishing a second Series of his Lectures.

ON THE ALTERNATION OF GENERATIONS; OR, THE PROPAGATION AND DEVELOPMENT OF ANIMALS THROUGH ALTERNATE GENERATIONS: A PECULIAR FORM OF FOSTERING THE YOUNG IN THE LOWER CLASSES OF ANIMALS. By Joh. Japetus Sm. Steenstrup, Lecturer in the Academy of Soro. Translated from the German Version of C. H. Lorenzen by George Busk. London printed for the Ray Society. 1845.

THIS work is calculated to excite much interesting speculation, as exhibiting some new phases in the process of generation, and also as throwing some light upon one of the most obscure points of physiology, the reproductive process of Entozoa. The title, extended as it is, will hardly convey to those unacquainted with the views of the author any very clear notion of the peculiar mode of propagation here described. This cannot, however, be a matter of surprise; for although, as Mr. Busk states, some glimpses of the subject were afforded by the naturalist Chamisso, in his observations on the apparent alternations of generation, so far back as 1819, and by the subsequent researches of Sars and Siebold on the development of the Medusa, and by those of Lovén on the development of Campanularia, &c., still no one, until the author of the present work, "appears to have entered upon the general question of the existence of an analogous course of development throughout the lower classes of animals." -(Translator's Preface, p. vi.) As the phenomena described by M. Steenstrup are so novel, we shall probably succeed best in conveying a knowledge of them to our readers, by prefixing a few general remarks illustra tive of the relations between them and the ordinary mode of generation.

1846.]

GENERATION Or Bees, Aphides, &c.

23

In all the forms of reproduction with which we are best acquainted, it is seen that the production of the new being is partly effected by powers inherent in the parents, male and female, and partly by powers inherent in the germ or embryo itself; the former effecting the primitive formation of the germ, whether that be accomplished by the male, by the female, or by these conjointly, for all these theories have their advocates; the latter, accomplishing the development or growth of the germ.

It is necessary to bear in mind that the individual modes of generation differ from each other essentially, only by the manner in which this second part of the process (development) is accomplished: it may be oviparous, ovo-viviparous, or viviparous, but in each case the germ is the sole agent of its own growth, however much the mode of its nutrition may vary. This law does not, however, exclude the indirect agency of the parents, principally the mother, in providing some of the necessary conditionssuch as a supply of nutritious matter, of heat, of protection, &c. Up to the present time the best known exceptions to these incidental processes being accomplished by the parents, and again we may observe almost exclusively by the mother, are furnished by bees, wasps, ants, and termites, among which interesting animals the curious provision of nursing is displayed, that is to say, individuals are met with having no other office than to provide food, heat, and protection for the young; an economy with which all are familiar, who know the proceedings of the bee-hive or ant-hill.

Although, as will afterwards be apparent, this system of nurses is a branch of the propagation of animals by the principle of "alternate generations," we would more specially fix the attention of the reader on the mode of reproduction which takes place among Aphides, because this in reality is a perfect type of the remarkable process elucidated in the present work.

"The propagation of these creatures through a series of generations has been already long known. In the spring, for instance, a generation is produced from the ova, which grows and is metamorphozed, and without previous fertilization, gives birth to a new generation, and this again to a third, and so on, for ten or twelve weeks; so that, in certain species, even as many as nine such preliminary generations will have been observed; but, at last, there always occurs a generation consisting of males and females, the former of which, after their metamorphosis, are usually winged; fertilization and the depositing of eggs takes place, and the long series of generations re-commences in the next year, and in the same order." P. 108.

In order to form a true notion of this most remarkable form of propagation, it is necessary to state that, as no immature or imperfect animal can form germs, the germs of all these generations must have been produced by the perfect and fertile individuals, the several intervening generations, excepting the last, standing simply in the relation of nurses, affording, like the nurse-bees, but in the interior of their bodies, nutritious matter, heat, and protection; so that we have here the curious spectacle of animals giv. ing birth to young without being parents, and of young proceeding from individuals of which they are not the offspring.

If this be the true view of the generation of Aphides, it becomes an interesting, and, in connexion with the general laws of ovology, an important question to determine the true sexual nature of the animals forming the

intervening generations, and the nature of their retentive genital organs. The history of social bees and wasps shows that the feeders or nurses are females, whose sexual organs remain in an undeveloped state; and Steenstrup affirms, what from this fact we should necessarily infer, that what he well terms "foster-parents," are among the Aphides also imperfect females; indeed, in every similar case, the multitude of individuals, to whom is committed the perfecting of a later generation, "consist invariably of females, the males being apparently excluded from any participation in the office, on which account the males of all the animals among which the system of 'nursing' or of' feeding' obtains, constitute a very subordinate number." (P. 111.) This conclusion is greatly strengthened by what next follows. Among the many interesting facts and generalizations of this philosophic investigator, there are none evincing more acumen than those relating to the nature of the retentive organ. M. Steenstrup well observes

"That the nursing' should be committed to females alone appears to us very natural, since we are acquainted with an organ in them whose natural function would be to perform that office. The generative organs are, indeed, in perfect (female) individuals, divided as it were into two parts of very distinct natures; the ovarium for the preparation of the germ and the production of the egg, and the oviduct and uterus in which the ova are as it were incubated, and the germ and embryo sufficiently developed to allow of its being born. Now, it is actually the case, that no true ovary has been discovered in the nursing' generations; on the contrary, the germs, as soon as they are perceptible, are situated in organs which must be regarded as oviducts and uteri, as, for instance, in the most perfect' nurses we are acquainted with, the Aphides." P. 112.

This is a most valuable and distinguishing fact, and not only throws a clear light upon the whole system of alternating generations, but also reconciles with the law already noticed, that imperfect individuals, namely, cannot form germs, what had hitherto appeared to be the anomaly of imperfect Aphides reproducing. We shall have occasion again to notice this point.

It is thus seen that, in this propagation by the agency of nursing animals, the business of generation, so far as the process of developing the new being is concerned, instead of being, as in ordinary reproduction, accomplished by one individual or mother, (we exclude for the moment those few cases in which the male assists in nourishing the embryo,) is, in this most remarkable process, divided among several different individuals.

We now proceed more particularly to point out the views of the author, and to detail some of the principal facts that have led to the theory he so ably advocates.

"The special subject of this Essay," observes M. Steenstrup, " is the fundamental idea expressed by the word Alternation of Generations,' or the remarkable, and till now inexplicable natural phenomenon of an animal producing an offspring, which at no time resembles its parent, but which, on the other hand, itself brings forth a progeny, which returns in its form and nature to the parent animal, so that the maternal animal does not meet with its resemblance in its own brood, but in its descendants of the second, third, or fourth degree or generation; and this always takes place in the different animals which exhibit the phenomenon, in a determinate generation, or with the intervention of a determinate number of generations. This remarkable precedence of one or more gene