48 



The Rot in Sheep. 



The generative appendage is strongly muscular, especially on 

 the side of its curvature, as is depicted by the lines there 

 drawn. In addition to its longitudinal order of fibres, it has 

 also a circular set, which are well developed. When fully 

 pressed out the appendage curves upon itself, and always in 

 proportion to the amount of pressure which is employed to 

 produce its exsertion. It is also found to have a cauliflower- 

 like projection at its extreme end, which otherwise appears to 

 be simply rounded in form. It is imperforate at its extremity, 

 for the duct which enters its base from the receptacle (b) within 

 its sheath only extends about a third part of the entire length 

 of the appendage, where it abruptly terminates. 



It has been supposed, but erroneously, that a canal runs 

 through the whole course of the organ, and in several illus- 

 trations such a passage is represented. We quote Professor 

 Owen's remark on this point, which must suffice to show the 

 general opinion of naturalists : " This appendage," says this 

 distinguished professor, " is spirally disposed when flaccid, is 

 tubular and distinctly perforated at the apex." * 



The extraordinary curving of the appendage upon itself when 

 completely exserted, and therefore under circumstances analogous 

 to its erection, seems to us to militate greatly against the opinion 

 of its being used as an intromittent organ, in the true sense of 

 the term ; whilst its size likewise negatives the idea that it can 

 be made to enter the mouth of the oviduct as it would have 

 to do in ordinary copulation. If contact for fructifying the ova 

 does take place between two distomata, but which we very 

 much doubt, it would appear that the generative appendage of 

 one could only enter the sulcus of the other, which is produced by 

 the retraction of its generative appendage into the sheath. When 

 fully retracted, however, the appendage appears to simply lie 

 within the sheath ; and it is very probable that its retraction 

 is chiefly for the purpose of giving a facility to the escape of 

 the ova from the oviduct, as previously explained. 



Nervous system. — In concluding our description of the anatomy 

 of the distoma we add one word respecting its nervous system. 

 Mehlis, some years since, described the nervous system of the 

 entozoon as consisting of " a delicate oesophageal filamentary 

 ring, with a slight ganglionic enlargement on each side, from 

 which minute fibres pass into the suctorial sphincter ; and two 

 large filaments pass backwards, one on each side, as far as the 

 ventral sucker" (Oiven). We are free to confess that up to this 

 time our investigations have not satisfied us of the existence of a 

 nervous system, nevertheless we see no reason to doubt Mehlis' 



* ' Lectures cm Invertebrate Animals.' 



