Freeman : OBSERVATIONS ON CIILOROCHYTRIUM. 197 



at an adult stage, the whole of the green protoplasmic contents 

 divides into a number of from 1030 nearly circular zoospores, 

 which escape through the neck-shaped portion. 



" Living in the thallus of various species of Schizonema, 

 Polysiphonia, etc. ; also on the Infusoria found at Howth." 



Wright states further that there are two kinds of zoospores, 

 large and small, the latter being the more numerous. 



Szymanski in 1878 described C. knyanum apparently identical 

 with the plant mentioned by Kny four years before as inhabiting 

 the tissues of Ceratophyllum demersum. This species was found 

 on Lcmna minor and possessed a cellulose button which did not 

 protrude farther than twice the thickness of its outer wall above 

 the epidermis of its nurse plant. 



Klebs published the results of his investigations on C. lemnce 

 in 1881. Chlorochytrium in the younger vegetative stages 

 contains a light green chlorophyll-bearing protoplasm with iso- 

 lated starch grains surrounded by a cell sap vacuole (see below, 

 pyrenoids) . In the later stages the grains increase in number, the 

 mesh-work of green bands becomes smaller, the chlorophyll 

 darker until almost opaque and the protoplasm finally becomes 

 coarsely granular. After a resting period of a week or more 

 the zoospores are formed by successive bipartitions of the cell 

 contents, at first by perpendicular, later by radially disposed 

 walls. 



The number of divisions is not known. Liberation of the 

 zoospores is accomplished by absorption of water resulting in 

 the splitting of the Chlorochytrium wall and of the superposed 

 Lcmna tissues. 



The conjugation of the biciliate zoogametes into larger 

 quadriciliate zoozygotes was observed, a fact which niay throw 

 light on the macro- and microzoospores of Wright's species. 

 Klebs observes that Cohn's account of the liberation of the 

 zoospores is without observational foundation and doubts its ac- 

 curacy. He also calls in question the appropriateness of placing 

 Wright's species in the genus Chlorochytrium and further sug- 

 gests the probability that C. knyanum is but the asexual form 

 of C. lemncg since no copulation had been observed between 

 the zoospores. C. -pallidum Klebs and many similar forms are 

 probably mere " place varieties" of C. knyanum. 



Klebs points out with much truth that no proof has been given 

 of the much averred parasitism of Chlorochytrium by Colin 



