DAMPING OFF. 251 



baryanum Hesse) says as stated above that the zoospores are oval 

 and provided with onecilium. Pythium equiseti 11 Sadebeck which 

 is generally considered to be the same plant, possesses two lateral 

 cilia according to the descriptions, and deBary only says that the 

 zoospore formation takes place in the oft described way. 18 In 

 Artotrogus proliferus^ (deBary), the author was unable to deter- 

 mine whether the zospores were uniciliate or biciliate. In the 

 vesicle they are figured as reniform, but the ultimate zoospores 

 are described as oval, one end being narrower than the other. 

 Double zoospores were also described which possess two light 

 spots instead of one. These ultimately divided, but before 

 division according to the author, the double zoospore was like that 

 of an organism controlled by two opposing wills. This was not 

 the case with the biciliated zoospores observed by myself in Arto- 

 trogus intermedius, until amoeboid movement was beginning 

 after a period of swarming, and when fission is about to take place. 

 Possibly deBary observed the "double" zoospores just at that 

 time. 



(In Artotrogus pyihiodes" (R. et C.) the zoospores are described 

 and figured as biciliate one cilium attached at each pointed end 

 of the zoospore exactly as I have found in the case of A. inter- 

 medius. But in A. pythiodes the authors say that the zoospores 

 absorb the two cilia, round off and germinate, i. e. they do not 

 divide, if the observations are clear on this point. This species 

 was found on leaves of Wolffia mitchellii. 



Other species of the genus are as follows. A. hydnosporus* 1 

 Mont, in potatoes and in dead seedling plants: 2Z A. ferax (deBary) 

 in dead insects and in dead seedlings in water. A. megalacan- 

 23 deBary in dead seedlings and parasitic in prothallia of Todea 



17 Untersuchungen iiber Pythium equiseti,Cohn's Beitr. z. Biol. d. Pfl. III. 

 117. 



l8 Zur Kenntniss der Peronosporeen, Bot. Zeit. XXXIX., 524, 1881. 



'9 Pythium proliferum deBary, Pringsh. Jahrb. f. wiss. Bot, II, 182, 1860. 



^Roze et Cornu, sur deuz nouveaux types generiques pour les Families des 

 Saprolegnees et dess Peronosporees, Ann. d. sci. nat. Bot. ser. 5, II. 72, 1869. 



21 Montague, sylloge, etc., p. 304, 1845. 



22 Bot. Zeit. XXXIX., 562, 1881. 



2 3 Beitr. z. Morph. u. Phys. d. Pilze. IV., 19, 1881 ; Bot. Zeit. XXXIX., 

 578, 1881. 



