INTRODUCTION 17 



It is of interest here to note one definite positive result 

 in favour of pleomorphism which was obtained by Wino- 

 gradsky himself. He records the growth of cells inside the 

 slimy covering of an organism which he has named Thiocystis 

 violacea. The cells which were at first globular were observed 

 to change shape and become elliptical until the length was 

 double the thickness. Then he observed the escape of these 

 altered cells from their slimy covering. The slime lost its firm 

 consistency, became swollen, and finally disappeared, thus 

 freeing the enclosed cells, which then disappeared from the 

 field of view in aggregated masses of varying sizes. The 

 removal was effected by their own organs of motility which 

 were probably cilia. 



An interesting piece of evidence in favour of pleomorphism 

 is supplied to us by Bavendamm in his study of Chromatium 

 Warmingii forma minus. Although this organism has been 

 studied by previous investigators the variation in question 

 was not observed until Bavendamm cultivated it under new 

 conditions, namely, the conditions of pure culture. The 

 result was the development of buds on the cells, somewhat 

 similar to the buds which normally appear on yeast cells. 

 Also the buds of different cells appeared to be able to effect 

 fusion as though preparatory to sexual reproduction. Al- 

 though this must not be regarded as a definite example of 

 pleomorphism, it does show that when the normal conditions 

 of growth are altered the organisms readily respond by chang- 

 ing their structure and normal habits. 



The Author's Investigations. 



The detailed life-history of the organism Thioporphyra 

 volutans is given in Chap. VIII. We may here, however, call 

 attention to the evidence in favour of pleomorphism which was 

 obtained by the investigation of this organism. The species 

 is normally a large uni- or diplo-coccus of a purple colour, 

 and with sulphur inclusions (Figs. 33-35). Under certain cir- 

 cumstances buds are formed on the cocci in great profusion, 

 and result in the culture fluid assuming a deep purple tint. 



2 



