BY G. I. PLATPAIR. 



Ill 



autospores. There is no need for the cell to be mature or even 

 free, and the customary inflation very often does not take place. 



Mother-cells. — It is to be deplored that comparatively little 

 attention is given in descriptions to the exact shape of the vege- 

 tative cell and of the apex, and so much to the details of the 

 mother-cell and the number of autospores. With regard to the 

 latter, it appears to me quite certain that any species may have 

 either 1, 2, 4, 8, or 16 autospores according to circumstances. 

 As for the mother-cell, I think 

 that its shape should not be 

 considered at all in the descrip- 

 tion or identification of an 

 Oocystis. It is generally pro- 

 duced by greater or less infla- 

 tion of the vegetative cell, and 

 the direction in which this 

 takes place is not necessarily 

 always the same. No doubt 

 the resultant shape depends 

 largely on the equality or inequality of the membrane, cf. 

 Eichler, Materyaly do flory wodorostow okolic Miedzyrzeca, 

 1894, T. ii., i.b,(fi,g. nostr.l) where a mother-cell of Eremosphrera 

 is shown with (S small but typical autospores. The original cell 

 had an incrassate membrane, and the inflation has obviously 

 blown out one side of the cell. It should be noted in passing 

 also that, whatever it was, the original cell was not a typical 

 Eremospha>ra\ towards the right-hand side, the relics of a slight 

 papilla or apiculus can be distinctly seen. 



Again, the apex of the vegetative cell is often incrassate 

 within, or there is an incrassate band round the extreme tip; 

 and when inflation takes place, this incrassation may be tough 

 enough to permit the apex to remain as a small papilla. This 

 would explain why the apical tubercle is so much more common 

 in the mother-cells than in the vegetative cells or autospores. 



Further, the mother-cell of any given species is not the same 

 shape as the vegetative cell, nor has each species a mother-cell of 



Text-fig. 1. 



E. r'iridis De Bary; mother-cell, 



( X 150); after Eichler. 



