238 MASSACHUSETTS HORTICULTURAL SOCIETY. 



meuting witli the supply of food. In cases where an amouut of 

 food was giveu which seemed inadequate to the needs of a com- 

 plete generation of zoospores and oospores, veiy few of the 

 normal zoosporangia and oogonia were formed, but the energy of 

 the plant was directed toward the production of the resting 

 sporangia. Thus it is evident that the insufficienc}^ of food may 

 directly prevent the appearance of oospores. It is not impossible 

 that the amount of the food supply and the prospect of immediate 

 support — or the reverse — ma}' at least regulate the formation of 

 zoospores as well. 



"When a new supply of nutriment is added to a culture which 

 has developed resting sporangia, the manner of renewing growth 

 depends somewhat upon the amount of nutriment added. If the 

 nutriment be supplied gradually, as by the decay of another tly in 

 close proximity, one finds that the tendenc}" is to jield zoospores 

 b}" the normal method, whereas, if a sudden addition of food is 

 made, as bj^ a decoction of flies or flesli, the vegetative tubes are 

 put forth in a manner essentiallj' similar to the germination of an 

 oospoi'e, and with a similar rejuvenescence of the resulting plant. 

 These considerations lead me to conclude that the resting zoospor- 

 angia are intermediate in function and structure between the 

 normal zoosporangium and the oogonium ; and, taken in connec- 

 tion with their similarity of position, and the remarkable parallelism 

 of the protoplasmic changes in the formation of their products, 

 offer much reason for considering the three structures as really 

 homologous. 



In conclusion, I would express my thanks to Dr. ^Y. G. Farlow 

 for valuable suggestions and the use of his library. 



Bibliography. 



Busgen : — Die Entwickelung der Phycomycetensporangien. II. 

 Saprolegniagruppe. Pringsheim's Jahrbucher, XIII, 1882. 



Dangeard : — Le Botaniste, April, 1890. 



Hartog : — On Formation and Liberation of the Zoospores in the 

 Saprolegnieae. Quarterly Journal Mic. Sci. Vol. 27. March, 1887. 



. Recent Researches on Saprolegnieje (a critical abstract 



of Rothert's paper). Annals of Botany, \'ol. 2. August, 1888. 



. Recherches sur la structure de Saprol^gnees. [188'.).] 



Rothert : — Die Entwickelung der Sporaugien bei der Saproleg- 

 nien. Cohn's Beitrjiafe. 1890. 



