Damping Off. 315 



develop parthenogeiietically. Fischer ^ places this in P. debaryanum. 

 A plant found in Lejpidiu'm sativxim^ and in Beta and 

 Sinapis by Lolide,io was described by him as Lucidium ])ytliioide& 

 and from the description there is little doubt that it is the Arto- 

 trogus deharyanus. L. cirGumdans described by the same author 

 in a fern prothallium ^^ develops only in the margin of the same, 

 producing short conidiophores and zoosporangia with 4-8 zoospores. 

 Fischer ^^ also includes this with P. deharyan'}Lv% Hesse, as well as 

 the Saprolegnia sohachtli ^'^ described by Frank in the thallus of the 

 liverworth Pellia epiphylla. Zoospores were not seen and oogonia 

 only rarely, the plant being usually sterile. 



A number of these are probably rightly referred to Artotrogus 

 deharya?ius {Hesse.) Unfortunately these plants can not well be pre- 

 served for study in their several stages and in most of the cases 

 probably no specimen of any stage has been preserved, so that it 

 would be quite impossible at the present time at least to speak with 

 any feeling of certainty on the proper disposition of these forms. 

 There is need of a thorough and comprehensive study of the species 

 of the genus, and considerable uncertainty will probably exist as to 

 the proper disposition of some of the above species until they can 

 again he found and critically studied. 



The fungus has been several times reported in this country, and 

 many notices of dampiijg off have been made without, probably^ 

 any serious attempt to determine the species. T. W. Galloway from 

 a careful study determined it from seedlings of G.ilia, Yiscaria 

 Lohelia, etc., in the Botanic Garden of Harvard University. He 

 did not, however, observe the zoospores. Humphey ^* also carefully 

 determined the species, but does not describe the zoospores. 



Damping or Prothallia. 



Artotrogxis intermedins {de Bary'). 

 This species was first noticed in fern prothallia growing in the 

 botanical conservatories of Cornell University in the month of 



9Rabenhorst'sKiypt. Flora. Pilze, IV, 404, 1892. 



lOUeber eiuif^e neue parasitisehe Pilze. Tagel>i. d. 47 Vers, deutscher Natnrf. 

 u. Aertze, 203, 1874. 



11 Ueber eiuige neue parasitisehe Pilze. Tagebl. d. 47 Vers, deutseher Naturf. 

 u. Aertze, 203, 1874. 



12 Rabenhorst's Krypt. Flora. Pilze, IV, 404, 1892, 4 Ibid. 



13 Notes on tbe fungus causing damping off, etc. Trans. Mass. Hort. Soe. 

 I, 1891. 

 14 8th Ann. Rept. Mass. State Agr. Exp. Station, 220, 1890. 



