THE URINARY ORGANS. 199 



structure of which will be afterwards described. The same 

 membrana propria which surrounds the tubuli uriniferi, also 

 somewhat thickened, (0-0005 — 00008'") invests these bodies 

 (fig. 247 a) ; and the epithelium is likewise continued into the 

 capsules thus formed, only that its cells are smaller and less 

 distinct and invest the vascular coil on the side directed 

 towards the canal of the emergent tubulus uriniferus. This 

 latter, generally somewhat constricted (fig. 247, B), is inserted 

 into the Malpighian capsule, most usually on the opposite side 

 to the afferent and efferent vessels; but in accordance with 

 what has been said, its cavity penetrates into the capsule, only 

 to an inconsiderable extent ; inasmuch as the latter is almost 

 entirely occupied by the vessels and the epithelium surrounding 

 them. 1 



[The ciliary motion discovered by Bowman in the neck o 

 the Malpighian bodies of the Frog and in the commencement 

 of the tubuli uriniferi, with the direction of the stream towards 

 the ureter, is readily confirmed, when the addition of water is 

 avoided. It is absent, however, in Birds (Gerlach thinks he has 



1 [With respect to the question of the caecal termination, or commencement, as it 

 might more properly be termed, of the tubuli uriniferi in the Malpighian capsules, 

 there is an apparent discrepancy of opinion among anatomists. Bowman states that 

 each tube commences in a Malpighian capsule ; whilst Gerlach says that the capsules 

 do not form the extremities of the uriniferous tubes, but are merely diverticula, 

 which communicate by a small neck with the angle formed by the uriniferous tubes, 

 winding through the cortical part of the kidneys ; or, as the same thing is described 

 by Leydig (1. c, p. 32), with respect to the kidney of the Sturgeon, two closely con- 

 tiguous, uriniferous tubules, are connected with the (Malpighian) capsule and con- 

 tinuous with it ; in other words, the tubules join in a loop, at the apex of which 

 is a globose diverticulum, in which the glomerulus is lodged; and, according to 

 him, the same arrangement obtains in the Reptilia. Now it seems that this dis- 

 crepancy admits of an easy explanation, for if we suppose the constricted neck of the 

 diverticulum to be lengthened into a tube, we have at once the disposition described 

 by Bowman, viz. a tube commencing in a dilatation containing the glomerulus and 

 afterwards anastomosing with another or with other tubules ; and if the neck of the 

 so-called diverticulum be very short, or, in other words, if the Malpighian capsule be 

 sessile, we have the arrangement described by Gerlach, &c. Mr. Toynbee's notion 

 that the tubulus uriniferus merely passes through the Malpighian capsule, forming 

 a coil within it, appears to us to be wholly inadmissible ; but many of the appear- 

 ances depicted in his very carefully executed figures (1. c.) would serve to support 

 the opinion that the Malpighian body is more often sessile than it would seem to be 

 from Bowman's account. — Eds.] 



