COXTRir.UTIOXS TO THE CYTOLOGY OF THE EACTEIJIA. 489 



The form of the nucleus is variable, not only in 

 different Bacteria, but also at different periods in 

 the life-cycle of the same species. 



The nucleus may be in the forn^ of a discrete 

 system of g-ranules (chromidia); in the form of a 

 filament of variable con figa ration ; in the form of 

 one or more relatively large aggregated masses of 

 nuclear substance; in the form of a system of irre- 

 gularly branched or bent short sti'ands, rods, or 

 networks; and probably also in the vesicular form 

 characteristic of tlie nuclei of m any anitnals, plants, 

 and protists. 



There is no evidence that enucleate Bacteria 

 exist. 



Finally, in addition to these purely morphological con- 

 clusions concerning the nucleus, I think anuther conclusion 

 is rendered highly probable : 



The Bacteria are in no way a group of simple 

 organisms, but rather a group displaying a high 

 degree of morphological differentiation coupled in 

 many cases with a life-cycle of considerable com- 

 plexity. 



Appexdix. 



On the Alleged Autogamy of Bacteria. — In two 

 earlier papers I have discussed the so-called "autogamy" of 

 the disporic Bacteria in some detail. The actual facts 

 regarding this process were recorded by Schaudinn (1902, 

 1903), and myself (1908). In a second paper (1909) I 

 brought forward strong evidence to show that the so-called 

 " autogamy " of Bacteria is not a sexual process at all, but has 

 a much simpler explanation. It seems necessary, howevei*, 

 to refer to this matter once more, owing to the recent 

 appearance of a very misleading* article by Dr. Euzicka.^ 

 After mentioning iSchaudinn's observations, the author 

 ' Y. Ruzii'ka, " Ueher die experinientelle Aiitogamie tier Bakterien," 

 ' Arch. Entw.-Mech.," Bd. xxx, Festschrift f. W. Roux, Teil. 1, p. 443, 

 1910. 



