Mr Dobell, On a so-called "sexual" method of forming spores, etc. 91 



On a so-called "sexual" method of forming spores in Bacteria. 

 By C. C. Dobell, B.A., Trinity College. 



[Read 22 February 1909.] 



Two species of Bacteria — Bacillus butschlii (Schaudinn) and 

 B. flexilis(Dohe\l) — are known which differ from all other Bacteria 

 in forming two spores instead of one in each cell. Before spore- 

 formation, the following remarkable phenomena are to be seen : 



A large individual begins to divide into two, but the division 

 is never completed, and all signs of it are subsequently lost. The 

 granules (? chromatin) in the cell then show streaming movements, 

 arrange themselves in the form of an irregular spiral in the long 

 axis of the cell, and finally heap themselves up at both ends of the 

 organism to form the two nucleus-like spore-rudiments. Round 

 each of these, a spore membrane is formed, so that the two spores 

 when fully formed lie at opposite poles. 



The process of incomplete division and subsequent fusion im- 

 mediately preceding spore-formation were considered by Schaudinn, 

 and also by myself, to represent a form of conjugation such as is 

 found in some yeasts, Heliozoa, etc. — that is to say, a conjugation 

 of sister-cells. 



From further investigations upon Bacillus spirogyra, Bacterium 

 lunula n.sp. and other Bacteria, it now appears to me to be certain 

 that no " sexual " process really occurs in the disporic Bacteria. I 

 believe that what has really happened is that the last bipartition 

 in the life-cycle — the one immediately preceding spore-formation — 

 has become abortive, and is not as a rule completed. The disporic 

 individuals are therefore really double individuals — physiologically, 

 but not morphologically. 



If this interpretation of the phenomena is correct, then it has 

 some interesting results : for instance, it has an important bearing 

 upon the problem of the affinities of the Bacteria. One of the 

 most important arguments in favour of the close relations of 

 Bacteria and yeasts is removed. It has also some significance 

 with regard to the problem of " sexuality " in the Protista and in 

 living beings generally. 



A discussion of these problems, and also of some special points 

 {e.g. the nucleus of B. spirogyra, etc.), will be given in my full 

 account of this matter, which I hope to publish before long in the 

 Quart. Journ. Microsc. Sci. 



