CHAPTER X
PROCHASKA, HYRTL AND ROKITANSKY, THREE OF THE MOST DISTINGUISHED TEACHERS AT THE MEDICAL SCHOOL OF VIENNA DURING THE EARLY PART OF THE NINETEENTH CENTURY
George Prochaska, born at Lipsitz, Moravia, in 1749, was appointed Professor of Anatomy and Ophthalmology at the Prague Medical School in 1778. Eight years later he was transferred to the Chair of Physiology. In 1791 he received the appointment of Professor of Higher Anatomy and Physiology in the University of Vienna. In 1819 he resigned this chair, probably owing to poor health; and his death occurred during the following year.
Between 1780 and 1797 he published, in Latin, important monographs on the physiology of man. Later, these were thoroughly revised and then published in German under the title of “Physiology, or the Doctrine of the Nature of Man.”
Prochaska was esteemed very highly as an eye surgeon of exceptional skill and wide experience, no fewer than 3000 cataract operations having been performed by him. His greatest achievements, however, belong in the domain of physiology. Already as early as in 1797 he hinted at the possibility that, in the case of the spinal nerves, one of the portions might transmit centripetal and the other centrifugal impulses. It was reserved, however, for the great English physiologist, Sir Charles Bell, to establish firmly, several years later, the law governing these two currents.
Prochaska’s ideas with regard to the nature of “vital force”—that question which in those days gave biologists so much trouble—may be inferred from the following quotations:—
In the performances of the nervous system there occur manifestations which bear a striking resemblance to the phenomena produced by electricity.... In my opinion it is not permissible to conceive of vital force as an independent power, one that depends upon a single and special principle, but rather as an aggregation of all the forces of Nature, representing in one set of instances the cause and in another set the effect of these forces, and combining in this body of ours, by their foreordained harmony, to create what we call life. Therefore, among the powers that are commonly meant when we use the expression “vital power,” there are no specific forces, but only the general forces which exist in Nature; but at the same time they are combined under a special relationship,—in fact, they are entangled the one with the other in such an inextricable snarl that it is simply impossible for us to gain a clear conception of their causes and effects.
Finally, it is quite remarkable, says Puschmann, how closely Prochaska’s ideas regarding the formation of bone agree with the teachings of our modern authorities. Here is the paragraph in which he formulates these ideas in full detail:—
The business of nutrition is carried on in such a manner that, when new conditions arise, whole organs which for some time previously were performing useful work, are swept out of existence, and new ones, better adapted to the work required of them, are put in their places. As an instance in point we may mention certain cartilages which, for a limited period of time during childhood, take the place of bone structures, and which at the same time play the part of really necessary aids to the growth of the bone. These cartilages gradually become converted into the latter tissue, the process reaching the stage of completion at different times, but yet at a fixed and definite time for each particular bone. Thus, in the case of the long bones, the cartilage becomes completely ossified somewhere between the twenty-second and the twenty-fourth year. This process of ossification does not consist in a simple hardening or change of the cartilage into bone; the essential features of the process may more correctly be described as follows: the cartilage, in the depths of whose substance bone-tissue centres are being nourished and are progressively undergoing development, is steadily being crowded to one side and ultimately destroyed. At the same time there appear here and there in the cartilage a few blood-vessels which, so far as one is able to judge, spring, in the majority of instances, from the neighboring fully-formed bone substance. And, as a further stage in the process of growth, there appear alongside the new blood-vessels centres of ossification, which in due time become foci of genuine bone tissue. Then, as these foci increase in size, the surrounding cartilage steadily dwindles in quantity until nothing remains but a few scattered cavities or hollows, which persist for only a short time before they disappear altogether.