GLANDS. 429 



a number of larger tubes, which terminate in the mammillary 

 processes which dip into the midst of the chambers called 

 chalices. 



According to the above description of the course and origin 

 of the tubes of the kidney, which is now the generally re- 

 ceived one, each tube commences in a single dilated extremity ; 

 it seems to me, however, to be probable that many of the 

 tubes have their origin in loops ; the fact of the occurrence of 

 loops throughout both the medullary and the cortical parts of 

 the kidney, the universal formation of loops on the surface of 

 that organ, and the non-existence of dilated extremities of 

 tubes on that surface, all tend to prove the correctness of the 

 view just mentioned. 



The tubes of the kidney, wherever encountered, consist of 

 a strong and structureless basement membrane (see Plate 

 LVIII. Jig. 1.); it is worthy, however, of especial notice 

 that these tubes, as well as their globular terminations, are all 

 inclosed in a framework constituted of a nucleated form of 

 elastic tissue. This framework is seen to most advantage in 

 cross-sections ; this it is which keeps the tubes distinct from 

 each other, and which explains the occurrence of intervals 

 between the tubes, seen especially in longitudinal sections. 

 (See Plate LVIII. fig. 2.) 



Malpighian Dilatations. It is certain that some, if not 

 all, of the tubes terminate in enlarged extremities. These 

 dilatations constitute the Malpighian bodies in part only ; 

 they are of a globular form, and their diameter exceeds 

 five or six times that of the tube itself. (See Plate LX. 

 ficjs. 2, 3.) They vary, however, considerably in size, in all 

 parts of the cortical substance of the kidney ; and Mr. Bow- 

 man states that they are largest near to the point of junction 

 between the cortical and medullary portions. 



The best way to obtain a satisfactory view of these bodies 

 is to tear up with needles a fragment of the cortical sub- 

 stance of the kidney, and to search amongst the divided 

 shreds for the Malpighian dilatations which are there met 

 with in all possible conditions. Some will be seen entirely 

 detached, lying loose in the water in which the fragment has 



