Notices of Irish Entozoa. 659 



ing with which we are acquainted ? If we can admit that 

 the formation of any portion of almost any Entozoon can be 

 referred to spontaneous generation, there will be but a very 

 narrow step to the hypothesis that all other animals, not ex- 

 cluding even man himself, may have a similar origin. 



Quitting this digression, I will now, though at the expense 

 of some repetition, note in a more systematic form the cha- 

 racters of the two individuals separately. 



I. — Cestoid Individual. — Generally oval or ovate, but va- 

 rying much according to its state of muscular contraction; 

 generally snow-white, enclosed originally by an outer cover- 

 ing of peritoneal membrane, and under this completely sur- 

 rounded by a regular cyst, with which it does not seem to 

 have any solid or continuous connexion ; substance parenchy- 

 matous, and without any internal cavity, except a sheath at 

 one end for its own proboscis, and at the other, a space for 

 lodging the nematoid individual ; proboscis broad, obcordate, 

 fringed (if not covered) with bristles projecting almost its own 

 length, retractile, and capable of being buried and rendered 

 invisible in its sheath ; ova none, but many granular points 

 occupying its substance throughout; no perceptible vessels; 

 contractile motion in every part, but most active towards the 

 proboscideal end. Vitality great, as it lives for several days 

 after the death of the animal it inhabits, and when divided, 

 the separated portions continue for a long time to contract 

 and relax. 



II. — Nematoid Individual. — When inclosed lies coiled in 

 a bent position, its head and body free, but its caudal point 

 attached to, and continuous with, the parenchyma or sub- 

 stance of the former ; can be easily detached entire, by tear- 

 ing the cestoid portion, but generally has a minute fragment 

 of the latter attached to its caudal apex, though it may some- 

 times be detached entirely free. 



When fairly insulated the following appearances may ge- 

 nerally be observed. — The animal is in constant motion, 

 stretching out and drawing back its head, or turning it from 

 side to side, the bothria at the same time assuming the form 

 of four hollow cups or suckers, dilating and contracting, and 

 thereby presenting a variety of shapes which it wou^ be next 

 to impossible to describe. When the animal is allowed to 

 lie on a slip of glass, either moistened with a solution of salt 

 or only a small quantity of fresh water, it will exhibit for a 

 long time no further appearances than those now mentioned ; 

 but let it be well washed by passing repeated drops of fresh 



Vol. II.— No. 23. n. s. 3 u 



