234 MASSACHUSETTS HORTICULTURAL SOCIETY. 



Pythiam described by Hesse under the name P. De Baryanum. 

 Saccardo gives as synonymous with it, 



P. equiaeti, Sadeb. 



Liicidium pythioides, Lohde. 



P. vexans, De By. 



The destruction of the fungus may be effected very readily by 

 subjecting the soil to conditions favorable for the germination of 

 the oospores before the time when it is desired for the reception 

 of the seeds. If, .in a few days, the soil be exposed thoroughly' 

 to a very dry, hot atmosphere, the very fragile vegetative hj'phie 

 will be destroyed, and a practical sterilization of the soil will 

 result. With proper subsequent care the likelihood of attack 

 will be very much diminished. Several methods of treatment to 

 be followed after the disease makes its appearance are given in 

 the " American Garden," as cited above. 



Since completing my observations on damping off, the notes of 

 Professor Humphrey, of the Massachusetts Agricultural Experi- 

 ment Station, have reached me. The two series of observation 

 were independently made, and inasmuch as they agree lend mutual 

 support. 



Bibliography. 



Damping Off. — American Garden, Vol. XI, No. G, June, 1800. 

 H. Marshall Ward: — Diseases of Plants. 



Pt/thium De Baryanum, etc. — De Bary : — Pythium vexans. 

 Botanische Zeitung, 1881. Hesse: — Pythium De Baryanum. 

 [Inaugural Dissertation, 1874.] 



II. Sapkolegnia monoica, Pringsheim. — It will perhaps not be 

 inappropriate to include with my brief notes on Pythium the results 

 of some observations on an allied genus, Saprolegnia. 



In the Autumn of 1890 I made a collection of material from 

 different localities in several states, with the purpose of securing 

 species of Saprolegnia which would present the most favorable con- 

 ditions for observing the nuclear action in the maturation of the 

 reproductive bodies. Of the forms obtained, S. monoica seemed 

 most suited to my use. The absence of thickenings on the wall of 

 the oogonium, and the possibility of obtaining depauperate sporan- 

 gia with only one or two oospores make the observation of iutra- 

 .sporangial conditions more easy. 



