REN. 



247 



tween the capsule and the vascular tuft, is 

 filled b_y fluid, in which the vessels are bathed, 

 and which is continually being impelled from 

 the capsule into the tube by the lashing move- 

 ment of the cilia. 



Fig. 157. 



This specimen has been chosen because it exhi- 

 bits the termination of a considerable arterial branch 

 wholly in Malpighian tufts, and because the several 

 Malpighian bodies injected show different appear- 

 ances of a very instructive kind, a, arterial branch 

 with its terminal twigs ; at a the injection has only 

 partially filled the tuft, at /3 it has entirely filled it, 

 and has also passed out along the efferent vessel, 

 e, without any extravasation, at y it has burst 

 into the capsule and escaped along the tube t, but 

 has also filled the efferent vessel e, at 2 and & it 

 has been extravasated and passed along the tube, at 

 m and m, the injection on escaping into the capsule 

 has not spread over the whole tuft. Magnified 

 about forty-five diameters. From the human sub- 

 ject. (After Bowman.} 



This very interesting phenomenon of ciliary 

 motion in the neck of the tube and in the 

 Malpighian capsule was discovered by Mr. 

 Bowman in the frog ; and at the time when 

 his paper was published he had not observed 

 it in any other animal. Mr. Simon* after- 

 wards observed it, as he says, " at the origin 

 of each uriniferous tubule in the kidneys of 

 various other reptiles, and also with perfect 

 distinctness in the skate." Bidderf has since 

 observed the same phenomenon in the triton ; 

 KollikerJ has described it in the embryo liz- 

 ard ; and I have seen it in the common snake. 



* A Physiological Essay on the Thymus Gland, 

 by John Simon, F.R.S. 

 f Miiller's Archiv. 1845. 

 t Muller's Archiv. 1845. 



From the frog; viewed by transmitted light. 

 Shows the continuity of the Malpighian capsule with 

 the tube, the change in the character of the epi- 

 thelium, and the vascular tuft, c, basement mem- 

 brane of the tube; b, epithelium of the tube; a, 

 cavity of the tube ; //, basement membrane of 

 the capsule ; d, epithelium of the neck of the 

 tube and of the neighbouring part of the capsule, 

 this epithelium is covered with cilia, which were 

 seen in active motion eight hours after death ; g, 

 detached epithelial particle, more highlv magnified, 

 showing the relative length of the cilia, as they 

 appeared in this specimen. The capillaries, m, lie 

 bare in the cavity of the capsule, having entered 

 it near t, where the view is obscured by another 

 tube. Magnified about 320 diameters. (After 

 J3owman.~) 



Fig. 159. 



Malpighian body from the newt (Triton). This 



