408 MALPIGHIAN CORPUSCLES OF THE KIDNEYS; [SECT. 187. 



the expansion of the proper membrane; it becomes smaller and 



less distinct, where it is stretched 

 across the glomerulus, at the point 

 where the vessels look towards the 

 cavity of the efferent tube. This 

 portion of the tubule (fig. 169, B) is 

 usually more slender than elsewhere, 

 and is attached to the Malpighian 

 corpuscle mostly at the side opposite 

 to the efferent and afferent vessels. 

 As has been mentioned, its cavity is 

 prolonged but a very little way into 

 the Malpighian corpuscle, for the 

 latter is almost entirely occupied by 

 the vessels and the epithelium. 



The ciliary movement with the direction 

 of the current towards the ureter, dis- 

 covered by Bowman in the frog, at the 

 neck of the Malpighian corpuscles, and at 

 the commencement of the tubules, can be 

 easily confirmed when the addition of 

 water is. avoided. It is absent in birds 

 and mammalia, but is found in serpents, 

 in the salamander, triton, bombinator, and 

 bufo. It is very beautifully seen in fish ; 

 and Remak and myself find it in the pri- 

 mitive kidney of the embryo of lizards, 

 which has the structure of a true kidney ; and in these two latter cases, 

 ciliary movement is also found in the tubules, at some distance from the 

 Malpighian corpuscles. 



The question of the existence of an epithelium over the glomerulus is not 

 yet finally set at rest, for very recently Todd and Bowman {Phys. Anat, ii. 

 p. 489) assert that the plexus is quite bare within the capsule. EcJcer and 

 others hold the same view. I may refer to my Micros. Anat., ii. 2, p. 354., and 

 only add here, that the primordial kidney and the true kidneys of amphibia 

 and fishes, are the most suitable places for demonstrating the epithelium over 

 the tuft of vessels. 



I shall only mention here some of the very frequent pathological degenera- 

 tions of the tubuli uriniferi. Their membrana propria is often thickened to 

 o-ooi'", or even 0-002'", and then frequently presents, on its inner side, very 

 beautiful, delicate strife, closely disposed in a transverse direction. The 

 epithelial cells, especially of the cortical substance, frequently contain a 

 considerable quantity of fat-globules, so that they then much resemble 

 hepatic cells from a fatty liver, the more so, as they are then generally en- 

 larged up to 0-02'" in diameter. Along with the fat, pigment granules (of 

 the colouring matter of urine ?) also appear in the epithelial cells, both of 



1. A human Malpighian corpuscle, A., 

 with the urinary tubule, B. ft arising 

 (Vomit. Magnified 300 times. Half-dia- 

 grammatical figure, a. Envelope of the 

 Malpighian corpuscle, continuing into 6. 

 tin/ membrana 'propria of the convoluted 

 urinifcrous tubules; c. epithelium of the 

 Malpighian corpuscles; d. epithelium of 

 the uriniferous tubule ; e. detached epithe- 

 lial cells;/, vas afferens; g. vas efferens ; 

 h. glomerulus Malpigldanus. 2. Three 

 ei ithelial cells, from convoluted tubules; 

 magnified 350 times; one with fat-drops. 



