92 



THE ANATOMY OF INVERTEBRATE!) ANIMALS. 



Another mode of a sexual multiplication, which has a sin- 

 gular resemblance to the process of partial yelk division, 



Fig. &.—Noctiluca miliaris.—e, gastric vacuole ; g, radiating filaments ; /, anal 



aperture (?). 



occurs only in the spheroidal JVbctilucce. The endoplast dis- 

 appears, and the protoplasm, accumulating on the inner side 

 of one region of the cuticle, divides first into two, then four, 

 eight, sixteen, thirty-two, or more masses ; the division of the 

 protoplasm being accompanied by the elevation of the cuticle 

 into protuberances, which, at first, correspond in number and 

 dimensions with these division masses. When the division 

 masses have become very numerous, each protrudes upon the 

 surface, and is converted into a free monadiform germ, pro- 

 vided with an endoplast, a beak, and a long tentacle, which 

 is hardly to be distinguished from a flagelliform cilium. 



The process of conjugation has been directly observed. 

 Two JVoctilucce, applying themselves by their oral surfaces, 

 adhere closely together, and a bridge of protoplasm connect- 

 ing the endoplasts of the two becomes apparent. The ten- 

 tacula are thrown off, the two bodies gradually coalesce, and 

 the endoplasts fuse into one. The whole process occupies 

 five or six hours. Spheroidal or encysted JSfoctilucm may 

 conjugate in a similar manner. In this case, the regions 

 nearest the endoplasts are those which become applied to- 

 gether. Whether this process is of a sexual nature, or not, 

 is not clearly made out. Cienkowsky admits that it may 



