68 MICROBES AND TOXINS 



the cells which join belong to the same strain, and to the same 

 generation or to two generations very near each other, this 

 conjugation in the yeasts is an example of isogamy. 



In the bacteria it has long been observed that multiplication 

 by transverse division, i.e., asexual reproduction, appeared to 

 be an absolute rule ; but Forster has described a species of 

 conjugation among the sulphur-forming bacteria; they come 

 together in twos or threes, put out little processes, unite and 

 finally separate ; this is a conjugation between individuals 

 which are doubtless differentiated, and resembles somewhat 

 the well-known conjugation of infusoria. 



The observations of Schaudinn on B. Butschlii have demon- 

 strated the existence of conjugation also among the bacteria — 

 at least among those which produce endospores. The ordinary 

 multiplication by transverse division exists in B. Butschlii, but 

 in the individual about to form spores, other peculiar 

 phenomena are seen : the individual begins by dividing into 

 two, but the septum disappears almost as soon as it is formed 

 and is dissolved, the two cells which had just been divided 

 by the septum melting again into a single cell ; an exchange 

 of chromatin takes place between them, and finally almost all 

 the chromatic granules collect at the two poles to form two 

 spores. Short as is the time that the septum remains, there 

 have, nevertheless, existed, during that moment, two cells 

 which have conjugated : and this is, according to Schaudinn, 

 a rudimentary sexual act. An analogous conjugation occurs 

 with B. Sporenema. 



It is really an autogamy or fusion between two elements of 

 the same cell, or to be more precise it is a conjugation between 

 two daughter-cells of the same mother-cell, and is hence called 

 paedogamy. 



Numerous cases of autogamy have been described among 

 the protozoa. Autogamy is the opposite of the amphigamy 

 which occurs when there is conjugation of two individals of 

 well-differentiated sex. 



What relations are to be established between these two 

 methods of fertilisation? Is autogamy the simple primitive 



