47 235 



the most conspicuous, carrying on its lop 7 — 9 menibranelles; laterally lo it arc two 

 ottiers, carrj'ing about six membranellcs of different size. AH this is in close accord- 

 ance with what we lind in the female; more ventrally in the same place, as in the 

 female, but more reduced are found two convergent lamelles, bearing on their borders 

 series of membranelles, diminishing in size dorsally ventrally; above these mem- 

 branelles again are two other elevations with a series of hairs, much more developed 

 in the female than in the male. The. two series of strong hairs which border the 

 mouth opening dorsally, I have not been able to find in the male. The hypodermal 

 cells of the corona have not been studied. 



The brain is rectangular, giving off nerves for the wheel-organ, but neither 

 thej' nor the retrocerebral organ have been subjected to a close inspection; the last 

 named seems to be very small, resembling in form that of the female; the openings 

 have not been detected. From the brain proceed nerves for the dorsal organ and 

 from the hind corners the long nerves for the lateral organs. I have hitherto been 

 unable to detect the two muscles which go to the dorsal organ in the female, though 

 they are most probably present. As in the female we find no eye spot. As all other 

 authors have pointed out, there is no alimentary canal. In accordance with Leydig 

 (1857, p. 411) the suspensor testis (Cohn) may however be regarded as a rudiment 

 of the alimentary canal. Seen laterally it maj' be shown that the suspensor testis, 

 which extends forward from the frontal border of the testis to the hypodermal cells 

 of the wheel-organ, being fastened just where the mouth parts are to be found in the 

 female, is directly continued in the remarkably well developed indusiura, which is 

 fastened dorsally to the transversal muscle bands at three to five points, and in 

 which further the testis is suspended. The form of this indusium ditTers from 

 specimen to specimen; it can only be observed laterally and has been well figured 

 by Weber (1888, PL 33, fig. 2) and mentioned by Leydig (1857, Tab. 16,fig. 3—4). 



When Weber states that the indusium is to be regarded as a real "réseau 

 musculaire", and that it is enveloped "par la continuation des masses granuleuses 

 représentant des rudiments du tractus intestinal" this is rather dificult to under- 

 stand from a histological point of view. Leydig's supposition, that the suspensor 

 testis and the indusium are parts of the rudiment of the alimentary canal, is more 

 intelligible, inasmuch as, according to him, it is said to contain "grosse Blasen mit 

 Häufchen solcher gelbbraunen Körner welche die Magencellen aller Rotatorien er- 

 füllen". The real connection between the testis, its modus of suspension and the 

 real derivation of the suspending tissues can only be studied in cuts. 



The excretorj' organ consists in two lateral canals which, directly below the 

 hypodermal cells of the wheel-organ, anastomose with each other, and are provided 

 with two slings, the one immediately below the wheel-organ, the other a little more in 

 the middle of the body ; there is no contractile vesicle though curiously enough it has 

 been indicated by all the earlier authors (Cohn, Leydig, Dada y and Hudson). Weber 

 supposes that they have seen with "les yeux de la foi" (1888 p. 43). It is much more 

 probable that, with the more primitive instruments at their command, they have 



