Anatomy of Aaslnduin A initluhid. 229 



word " cilia " will be used instead of '" Hagella '" for convenience 

 — though the Ifutter is undoubtedly more correct.] In number 

 tho nephrostomes vary considerably — from 150 to 200 — [Cf. 

 Rana catesbiana with 150 at moi^t, and R. esculenta with 250 to 

 360, Farrington, '93]. In diameter they average in this form 

 0.04 mm., i.e., somewhat larger than in Rana ; in length or 

 depth, the funnel averages 0.09 mm. In H. aurea we occasional- 

 ly find long branched ciliated tubules present as direct internal 

 prolongations of the funnels, these run parallel to the surface, or 

 •at other times towards the centre of the kidney for about one- 

 third of its thickne.-s, from the ventral edge. I have not 

 been able to detect any division or union of these finer tubes, 

 such as has been described by Spengel in Rana [Spengel, '77, p. 

 330]. Not infrequently, a large funnel is seen close to the outer 

 edge of the kidney where the parietail pea-itoneum leaves the 

 kidney to become attached to the body-wall. 



The effects of the activity of their cilia may sometimes 

 be seen on the surface of the kidney, in the currents set up by 

 their movement, e.g., when the living kidney is placed in salt 

 solution containing finely divided carmine. In such a case, in 

 H. aurea, I have seen undoubted though small movement of the 

 suspended particles of carmine, all external source of movement 

 having been carefully eliminated — although Haslam and Farring- 

 ton state that they hajve been unable to detect any such evidence 

 of ciliary movement, in the forms examined by them. 



Tlieir interaal relations are by no mejins easy to make out, 

 owing to two circumstances. Not only must the internal open- 

 ing (if such exisit) be very minute, else the corpu'^cles may be 

 forced through it outwards, but it is also extremely likely that 

 even if it be not collapsed at death, it will contract during 

 fixation. After the examination, however, of numerous com- 

 plete series of sections, amounting to many thousandis in num- 

 ber, there is not the s.lightest doubt as to the existence of 

 an internal opening [Cf. Pi. XXI., fig. 3], and that this leads into 

 the Renal Veins, or into blood -spaces directly continuous with 

 these veins, the long cilia protruding into these cavities aimong 

 the corpuscles nmch in the s^mxe way as in Rana [Bles, '98, p. 

 75; Howes, PI. VII., Figs. XXXV., XXXVI.]. The actual in- 

 ternal opening has only been found in other forms among the 



