BY G. I. PLAYFAIR. 



116 



Text-fig. 4. 



autospores, In my opinion, it is, biologically, the mature form 



of the genus Oocystis, the varieties of which are really forms of 



one true species, in a greater or less degree of reduction. 



Mevibrane. — In the typical, spherical forms, the membrane is 



generally stout ( x 1-2//.) but simple, and sometimes it is the same 



also in the other forms. Generally, however, the latter have 



this membrane lined with a thick, mucous 



structure ( x 4/i. or so), which is usually 



longitudinally corrugated into rather broad 



gores. More rarely, the mucous lining is 



also marked by two or three horizontal 



corrugations just below the polar cap. In 



one specimen that I noted, the mucus was 



thinner, and sulcate in such fine wavy lines 



as to pre.sent the appearance of watered „ .... .^, ,. ., , 

 ^ ^^ A. rirtdis, with digitate 



silk. Var. nodosa often has the mucous diloroplasts ( x 370). 



lining covered with shallow depressions, so 



that the membrane appears to be very coarsely scrobiculate. 



Chlorojjlasfn. — The chloroplasts are usually minute, parietal 

 discs ( X 4-6//.), but not, as far as my recollection goes, in lines, 



or adhering to one another (c/! G. 8. 

 West, Brit. Frw. AlgiB, p.229). Nor have 

 I come across any cells with radiating, 

 laminar chloroplasts as figured by Chodat, 

 Bot. Zeit., liii., T. v., f.6, 7. Sometimes, 

 however, the chloroplasts are minutely 

 fusiform or digitate (Text-fig. 4) as in 

 Oocyst is oval is, and, when this is the case, 

 tliey have a tendency to lie along the 

 strands of protoplasm by which the nucleus 

 is suspended. Occasionally, the ends of 

 these protoplasmic strands foi'ui a kind 

 of cellular network on the sui'face of the cell-wall (Text-fig. 5), and, 

 to this network, the chloroplasts adhere. 



After I'evivification of a previously dried habitat, cells of IJre- 

 mosphcera are often found in which the chlorophyll has been 



Text-fig. 5. — E. mridix, 

 with chloroplasts edg- 

 ing a pseudocellnlar 

 structure,! x330). 



