CONTEIBUTIONS TO THE CYTOLOGY OF THE BACTERIA. 483 



of the spore. These two different nuclear conditions therefore 

 coincide very definitely with two different phases of the life- 

 cycle. 



In Bacillus spirogyra and allied oi"ganisms — as I have 

 shown (1909) — two nuclear conditions are also found. ^ In 

 the ordinary vegetative part of the life-history the nucleus 

 is in the form of a filament. A part of this gives rise to a 

 large, aggregated spherical mass of chromatin which enters 

 into the spore. Here, again, the nuclear changes are corre- 

 lated with definite stages in the life-history. I have not 

 studied the young Bacilli which emerge from the spores in 

 any organism of the spirogyra type. I cannot therefore 

 state with certainty that the observed nuclear changes are the 

 only ones which exist. On analogy with B. saccobran chi, 

 it is quite possil)le that a chromidial condition of the nucleus 

 occurs in Bacteria of this sort. 



I have shown that three different nuclear conditions exist 

 in three different species of Spirilla which I have studied. 

 If one can argue on analogy in this case, it appears not 

 improbable that these nuclear conditions are temporary, and 

 that other phases in the nuclear structure exist in these 

 organisms also. It is quite possible, for example, that the 

 nuclear filament in the Spirillum from the intestine of 

 Lacerta muralis may at other stages in the life-cycle — as 

 in Bacillus sac cob ranch i — become modified into the 

 chromidial form of nucleus which exists in such an organism 

 as S p . ra o n o s p o r a . 



My own belief is that the nucleus in Bacteria may 

 d i s p 1 a y n o t o la e , but many forms during the whole 

 life-cycle. Many of the nuclear structures which have 

 been shown to exist in these organisms should, I think, be 

 regarded as temporary stages rather than as permanent 

 conditions. The different results which have been reached 



^ It may be emj)liasised also that the spiral filament itself in Bacteria 

 of this type shows a wide latitude of variation in form. Whether these 

 variations are correlated with special stages in the life-cycle is as yet 

 tmkuown. 



