OF MICRO-ORGANISMS. 73 



nomenon is still different: the nucleus, at first massed 

 together in a cluster, lengthens out into a very long 

 string, which breaks; and the pieces becoming scat- 

 tered about in the protoplasm, are absorbed. 



We find that fecundation in every instance intro- 

 duces the dispersion and disappearance of the old nu- 

 cleus and that the latter is replaced by a new nucleus 

 resulting from the transformation of the attendant nu- 

 cleus that proceeded from the other organism. 



The various modifications presented by this atten- 

 dant nucleus likewise contribute in great measure to 

 the complexity of the phenomenon. We have seen 

 that in the Chilodon the attendant nucleus breaks into 

 two globules, of which one goes to form the new nu- 

 cleus and the other the new attendant nucleus. Mat- 

 ters take a different course in the Paramaecia. In the 

 Param&cium bursaria, for instance, the attendant nu- 

 cleus divides into two and then into four capsules; 

 one of these capsules suffers absorption, a second one 

 becomes the attendant nucleus, and the two others 

 coalesce with what remains of the old nucleus to form 

 the nucleus proper. In the Paramcecium aurelia the di- 

 vision is made into eight capsules; three are cast out, 

 and of the five left four are meant to form the new 

 main nucleus; in reality, each Paramaecium segmen- 

 tates first into two and then into four divisions, and 

 each of these four individuals takes one of the capsules. 

 The fifth capsule is designed to form the attendant 

 nucleuses of these four organisms; it divides, accord- 

 ingly, into two and then into four parts; that is to say, 

 into as many parts as the body of the animal divided. 



There is no question in our mind but that conjuga- 

 tion in this case is a sexual phenomenon. A circum- 

 stance that at the outset confirms this is the peculiar 



