No. 590] 



THE EVOLUTION OF THE CELL 



113 



closures. With still further increase of size the chroma- 

 tin-grains also increase in number and may take on vari- 

 ous types of arrangement in clumps, spherical masses, 

 rodlets, filaments straight or twisted in various ways, or 

 even irregular strands and networks, 23 and the cytoplasmic 

 matrix, if it is correct to call it so, becomes correspond- 

 ingly increased in quantity. I will not attempt, however, 

 to follow up the evolution of the bacterial type further, 

 nor to discuss what other types of living organisms maybe 

 affiliated with it, as I have no claims to an expert knowl- 

 edge of these organisms. I prefer to leave to competent 

 bacteriologists and botanists the problem of the relation- 

 ships and phylogeny of the Cyanophyceae, Spirochetes, 

 etc., which have been regarded as having affinities with 

 Bacteria. 



(2) In the evolution from the biococcus of the pred- 

 atory type of organism, the data at our disposal appear 

 to me to indicate very clearly the nature of the changes 

 that took place, as well as the final result of these changes, 

 but leave us in the dark with regard to some of the actual 

 details of the process. The chief event was the forma- 

 tion, round the biococci of an enveloping matrix of proto- 

 plasm for which the term periplasm (Lankester) is most 

 suitable. The periplasm was an extension of the living 

 substance which was distinct in its constitution and prop- 

 erties from the original chromatinic substance of the bio- 

 coccus. The newly-formed matrix was probably from the 

 first a semi-fluid substance of alveolar structure and pos- 

 sessed two important capabilities as the result of its phys- 

 ical structure ; it could perform streaming movements of 

 various kinds, more especially amoeboid movement; and 

 it was able to form vacuoles internally. The final result 



" See especially Dobell, "Contributions to the Cytology of the Bac- 

 teria," Quart. Journ. Micr. Science, LVI (1911), pp. 461, 462. I can not 

 follow Dobell in applying the term ' ' nuclei ' ' to these various arrangements 

 of the chromatin-grains in Bacteria. Vejdovsky compares them with chro- 

 mosomes; but there is no evidence that they play the part in the division 



romatin-grains which is the spe 



