593 



On Changes in the Glomeruli and Tubules of the Kidney 

 accompanying Activity. 

 By T. G. Brodie, MJX, F.K.S., and J. J. Mackenzie, M.B. 



(Received December 9, 1912,— Read February 20, 1913.) 



(From the Physiological and Pathological Laboratories of the University of Toronto.) 



[ Plate 27.] 



The experiments described in this paper were designed to test the 

 correctness of the view put forward by one of us * namely, that the 

 glomerulus is a propulsor. If this view be correct, the marked dilatation 

 of the tubules, which is so prominent a feature in a kidney after active 

 diuresis, is simply the expression of the forcible distension of the tubule 

 from within, effected by the discharge of fluid from the glomerulus down 

 the tubule, the active propelling and dilating force being the intraglomerular 

 blood - pressure transmitted through the glomerular capillary cells and 

 epithelium. As, however, the condition of the glomerulus after active 

 secretion has not been made the subject of extensive observation, it seemed 

 probable that a thorough study of the alterations in size and appearance 

 of both tubule and glomerulus might give many points of importance in 

 criticising the propulsion theory. Thus, if the capsule be free to expand, we 

 may find it enlarged after active diuresis ; and again, if the propulsive action 

 of the glomerulus is complete and instantaneous, we should find the 

 glomerulus filling Bowman's capsule completely under all conditions. But 

 it was also possible that, after a very free secretion of water, there might be 

 a considerable accumulation of fluid between the glomerulus and the capsule 

 wall. We therefore measured the sizes of the capsules, the glomeruli and the 

 tubules in kidneys, before and after diuresis had been set up under varying 

 conditions. The more important of these states were : — 



1. The kidney at rest. 



2. The kidney secreting freely. This we term an " active free " kidney. 



3. Decapsulated and secreting freely. This we term an " active decapsu- 

 lated " kidney. The aim of the procedure was to test the explanation 

 offered by the theory as to the meaning of the Capsule.f 



* Vide Croonian Lecture, supra. 



t As in the course of this paper we shall be referring constantly to the Capsule of the 

 kidney and to Bowman's capsule, we will, in order to avoid needless repetition, distinguish 

 between them by employing a capital letter whenever we refer to the former. 



