TRANSACTIONS OF SECTION D. DEPT. ANATOMY AND rHYSIOLOGY. 571 



colouring matter had been accumulated by tlie epithelium of the com-oluted tubules 

 from the lymph bathing the tissues, and which contained so little colouring matter 

 as to appear colourless. If a sufficient time had elapsed after the injection, the 

 colouring matter -was found in the form of granules or minute crystals lying on the 

 inner side of the cell in the lumen of the tubules. 



Bownum, as I have already mentioned, had in the case of the boa constrictor 

 studied in detail the blood-supply to the organ, which, as Jacobson had shown, 

 ditiers in tishes, birds, and reptiles from the mode of arrangement prevailing in 

 mammals. 



l?owman had shown that in the boa the glomeridi derived their blood exclu- 

 sively from, the renal artery, and the convoluted tubes exclusively from the common 

 iliac vein. Nussbaum ga^e absolute completeness to the proof of Bowman's theory 

 by the following remarkable experiment. Experimenting on the newt, in which 

 the blood-supply of the kidueyis similar to that of the boa, he found that, when he 

 tied the renal artery, he arrested almost entirely the secretion of water in the kidney, 

 but that the excretion of urea and other solid matters, and amongst others of the 

 colouring matter already used by Heideuhain, viz. indigo carmine, continued. 

 Ligature of the renal branches of the common iliac vein stopped the secretion of 

 organic solids without impeding that of water. 



Tke most recext Theories .advanced in Explanation of the Phenomena of 



Glandular Secretion. 



Having brought before you the most salient facts with which we are acquainted, 

 ■which appear to throw the most light upon the general physiology of glandular 

 secretion, I wish, before concluding, to speak of the theoretical views which have 

 been advanced in explanation of a large number of the facts. 



In the first place, I have to confess that our ignorance is absolute as to the 

 cause (jf the specific endowment of different secretmg cells, in virtue of which they 

 produce new bodies at the expense of certain of the materials supplied to them by 

 the lymph, or separate particular constituents from the lymph, to the exclusion of 

 others which are equally abundant in the liquid. We express the full measure of 

 our ignorance when we state that the difference in function of different gland-cells 

 is due to differences in endowment of the protoplasm of the cell, which in no case 

 is explained by any objective characters of the cell. 



The phenomena of the secretion of water, which forms so large a part of every 

 .secretion, have given rise, however, to numerous speculations, concerning which I 

 may make a few remarks. 



The primitive view that the glands are organs in which is strained oiF from 

 the 1)1(10(1 water holding certain substances in solution has, in a modified manner, 

 found tinour with, some even to our own days, and appears indeed, at first sight, to 

 be borne out by certain facts. Thus within wide limits the amount of water se- 

 creted by the kidney depends upon the pressure of blood in the glomeruli. Any 

 circumstances which will lead to an increase of pressure in these vessels (as increase 

 of blood-pressure generally, division of renal nerves, division of the splanchnics, 

 especially when combined with stimulation of the spinal cord), by dilating the 

 branches of the renal artery, will lead to this resvdt. At first this woidd seem 

 to show that the process of separation of water, in the kidney at least, is but a 

 process of filtration, though a remembrance of the famous experiment of Ludwig, 

 referred to at an earlier period, on the relation between the pressure of secretion 

 of saliva and that of the blood in the arteries, would impose caution in drawing 

 the conclusion. \\Tiat are the facts, then, relating to the blood-pressure in vessels 

 in other organs of the body, and the transudation of liquid from them ? 



If an increased arterial pressure led ijiso facto to an increased transudation 

 through the capillary walls, it woidd follow that the amount of lymph and the 

 pressure of the lymph-stream would rise with the rise of the arterial pressure, but 

 direct experiments on this matter have led to an opposite conclusion. The experi- 

 ments of Pa.schutin and Emminghaus, carried out under Ludwig's direction, have 

 shown that when the arterial pressure in the extremities is increased, there is no 



