92 



THE ANATOMY OF IXVERTEBRATED ANIMALS. 



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

 gular resemblance to the process of partial yelk division, 



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



aperture (?). 



occurs only in the spheroidal Koctilucm. 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, corresj^ond 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 Noctiluca^ 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 JYoctihtcce 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. Cicnkovvsky admits that it may 



