804 SUMMABY OF CURRENT RESEARCHES RELATING TO 



came to rest, invested themselves with a cell-wall, and germinated 

 like the zygozoospores, putting oxit germinating tubes. 



Phi/llohium incertum, a nearly allied species, occurs in dead leaves 

 of Graminete and Cyperaceas. The resting-cells are of a bright red 

 coloui*, owing to the chlorophyll being more completely changed into 

 heematochrome. No conjugation of zoospores was observed ; and it 

 may be only a small non-sexual condition of the other species. 



Large green resting-cells found in dead branches and leaves of a 

 species of Hypnum were referred by the author to yet another 

 species and genus, Scotinosphcera paradoxa. They were of essentially 

 the same structure as the resting-cells of two species of Phyllohium ; 

 but the mode of formation of the zoosiDores presents a remarkable 

 difference. The entire protoplasm of the resting-cell becomes 

 extremely finely granular, the hajmatochrome entirely disappearing. 

 A variety of changes take place in the protoplasm, resulting in the 

 formation of a dark bluish green spherical mass, surrounded by a 

 protoplasmic fluid which is filled with red granules. The central 

 mass gradually enlarges, and divides into two and then into four ; 

 and then still further by repeated bipartition ; finally resulting in 

 the production of zoospores, which are narrowly fusiform, about 

 9*3^ long and 3 • 1 ^ broad, with a long colourless apex to which are 

 attached two cilia. No conjugation of zoospores was observed ; they 

 round themselves off and become invested with a cell-wall ; the sub- 

 sequent development of the resting-cells requires further investigation. 

 A very similar structure was also found endophytic in Lemna trisulca, 

 which may probably be a variety of the same species. It is probably 

 altogether non-sexual ; or conjugation of zoospores may possibly take 

 place on the close of a number of non-sexual conjugations. 



Dr. Klebs points out the transition from Phyllohium, in which con- 

 jugation takes place only between zoospores from different cells, to 

 Chlorocliytrium, in which the two sexual cells result, by bipartition, 

 from the same mother-cell, and which probably represents the 

 simplest form of sexual reproduction. 



The author disputes the correctness of the term parasitic applied 

 to these or similar endophytic algsB by Wright, Archer, Eeinke, and 

 others. They invariably contain chlorophyll, and always live so near 

 the surface of the host that abundance of light can reach them. 

 Their object in penetrating the tissue of aquatic and other plants is 

 merely to find a favourable situation for the development of their 

 resting-cells. 



The forms now described must evidently be classed under the 

 Protococeace« ; and the following may be given provisionally as their 

 diagnoses : — 



Chlorochytrium Cohn. Each cell breaks up, by repeated bi- 

 partition, into spherical zoospores, which, escaping from the mother- 

 cell, conjugate within the surrounding gelatinous envelope ; the 

 zygozoospores, already enclosed in a cell-wall, penetrate the inter- 

 cellular spaces of living plants by means of a germinating tube. 

 During the period favourable to growth several generations succeed 

 one another in one year, the latest hibernating in a resting state. 



