Notes on a New Boveria species. 5 



n. Conjugation. 



In all well investigated ciliates, conjngation is known to take 

 place after fissions frequently repeated during a prolonged period. 

 This is also the case with the present species, the conjugation 

 occurring periodically. As the large number of individuals living 

 inside the respiratory tree of the same host must have originated 

 from a single or a few progenitors and should have passed ap- 

 proximately the same number of generations, they may reasonably 

 be assumed to be at a given moment all nearly the same in their 

 physiological condition. Probably this explains to a degree why 

 in Boveria labialis the majority of individuals in the same host 

 are found simultaneously in conjugation, if they are found at all 

 in that stage. It is, therefore, necessary to take several holothuri- 

 ans infested by the ciliates, in order to obtain the different stages 

 of this reproductive phenomenon. Good permanent preparations 

 were made by lightly smearing the respiratory tree containing the 

 parasites on slips, and by treating with Schaudinn's solution, 

 afterwards staining with iron-haematoxylin and orange-G. We 

 also prepared sections, making use of various combinations of 

 fixing and staining reagents, but with no specially recommendable 

 results. 



The conjugation of Boveria belongs to the isogamous type. 

 Nevertheless, it presents some interesting points of deviation from 

 the common type attributed to the Ciliata. To mention some of 

 the most remarkable points ; (1) the two conjugants come into 

 mutual attachment wàth their aboral ends, instead of wâth the 

 oral ; (2) the meganucleus in each conjugant does not disappear,, 

 as it usually does, but persists after conjugation, eventually be- 

 coming coalesced with derivatives of tlie original synk avion ; (3) 

 the micronucleus of each conjugant undergoes divisions, of which 



