552 Notes. 



tail of the sphere being slightly longer) assist in swimming like 

 the leaves of a paddle-wheel, the alga turning a somersault by 

 their aid. 



It is found in the ditches all the year through, but has two 

 "swarming" periods — February, just after the keen frosts, and 

 again in early October. At such periods it may be collected 

 " pure " as it migrates in the water, as it were, in the form of 

 clouds. At other times it mixes freely with Eaglena. 



In size, apart from the processes, it approaches Sphcerella 

 nivalis. 



Multiplication proceeds by the chlorophyll contracting to the 

 sphere and dividing into two large oval portions. In these two 

 portions the chlorophyll contracts to the base of each, leaving the 

 fore end almost clear (plate XIV, fig. 2). 



Division goes on to four portions which evolve into the parent 

 form (zoogonidia). (Plate XIV. figs. 3, 4). 



In other spheres the chlorophyll divides up into smaller por- 

 tions which likewise assume the parent form (gametes). (Plate 

 XIV. fig. 5.) 



After prolonged active movements in the cell these forms break 

 through and swim in pairs, and I noticed a constant exchange of 

 partners. This is doubtless a form of true conjugation, though I 

 was not fortunate enough to trace results. 



There are further phenomena which I have frequently observed 

 and which appear to me to be referable to multiplication. 



The chlorophyll splits up in many cells into minute green 

 spherules, as far as I could count about sixty-four in number. 

 These spherules escape and are provided with four fiagella apiece. 

 These likewise swim in pairs (plate XIV. fig. 6). 



In correspondence with me, Mr. West would refer this 

 phenomenon to a pathological condition, and he states that such a 

 condition may often set in before the organism as a whole is really 

 dead. This did not appear to me to be such a- condition. The 

 collection was pure. As the alga swims about in " clouds " or 

 " colafties " it is easy to obtain it quite pure, and the peculiar 

 4-flagellated zoospores arising from this division preclude this 

 supposition of pathological condition. 



Another phenomenon which I referred to at the meeting as 

 formation of "bud cysts'" is very common with this alga. A 

 pellucid sphere forms in the chlorophyll, then another, sometimes 

 three or four. By-and-by zoospores, uniflagellate, can be clearly 

 made out within these pellucid spheres (plate XIV. fig. 7). 



These spheres become somewhat pear-shaped and penetrate 

 the envelope of the alga and are detached. They burst, and the 

 zoospores escape, having a remarkable resemblance to the sper- 

 matozoon of Homo. 



I at first took this to be a stage in the evolutiou of the alga, 



