AN ATOMY, OF THE KIDNEYS. 153 



accurately described and figured, in IS^S, 1 and the later con- 

 firmatory observations of Kolliker,* Isaacs, 8 and numerous 

 other anatomists. It only remains to describe the charac- 

 ters of the cells as compared with those lining the convo- 

 luted tubes, and to ascertain whether they line the capsule 

 alone, or are also attached to the vascular tuft. 



Bowman believed that the cells, when they existed, 

 simply lined the capsule, and that the blood-vessels were en- 

 tirely bare ; while Gerlach described cells attached to the 

 blood-vessels, and Isaacs regarded these cells as entirely dif- 

 ferent from those attached to the membrane. From the 

 great number of observations made by Isaacs upon the kid- 

 neys of different animals, there can be hardly any doubt 

 concerning the correctness of the latter view ; for not only 

 did he describe minutely the difference between the cells of 

 the capsule and those attached to the tuft, but he found that 

 the walls of the cells of the capsule were dissolved by dilute 

 nitric acid, " while comparatively little effect was produced 

 upon those of the tuft, thus showing a difference in their 

 constitution and organization." * We must, therefore, rec- 

 ognize in the Malpighian body two varieties of cells, differ- 

 ing in size, form, and situation ; one variety lining the cap- 

 sule, and the other covering the vascular tufts. 



Nearly all observers who have studied the anatomy of 

 the kidney practically agree that the cells attached to the 

 capsule are smaller and more transparent than those lining 

 the convoluted tubes. They are ovoid, nucleated, and finely 

 granular. The cells covering the vessels, however, are larger 

 and more opaque, and resemble the epithelium lining the 

 tubes. They measure from I4 1 0o to 10 1 00 of an inch in diam- 

 eter, by about ^ 5 \ Q of an inch in thickness. 



Tubes of the Cortical Substance. Following out the 

 tubes in the cortical substance from the Malpighian bodies, 

 we find first a short, constricted portion, which has sometimes 



1 GERLACH, op. c'd. 8 Loc. cit. 3 Loc. cit. 4 ISAACS, op. cit., p. 405. 



