166 
PUBLICATIONS (1916, 1927) 
Present status of the problem of the effect of radium rays on 
plant life. Mem. New York Bot: Gard. 6: 153-160. 31 
August, 1916. (Brooklyn Bot. Gard. Contributions, No. 
Is. 
Chromosome and gene mutations in Datura following exposure 
to radium rays. Proc. Nat. Acad. Sci. 13: 75-79. Feb- 
ruary, 1927. (Brooklyn Bot. Gard. eee ae No. 
49.) (With A. F. Blakeslee.) 
PATHOEGG Y 
Project 1. Disease Resistance in Plants 
Scope: 
1. The determination of the presence or absence of resistance in 
particular hosts to certain parasites. 
2. The influence of external conditions upon resistance and sus- 
ceptibility of hosts to particular parasites. 
3. The possible physiologic specialization of parasites. 
4. The essential nature of disease resistance. 
5. The inheritance of the disease-resistant quality. 
In these studies it is planned to use whatever suitable material 
is available. During the past few years the investigations have 
been carried out with the cereals and the cereal smuts, since these 
offer special advantages in the prosecution of the general problem. 
Status: 
Extensive studies on the varietal resistance of various cereals 
to their specific smuts have been carried out. The more extensive 
experiments have been with oats and sorghum. As a result of 
these studies a few varieties have been found to be resistant. 
Some knowledge of the influence of external conditions, such as 
temperature, moisture and soil reaction, has been obtained and 
served as a basis for the prosecution of other phases of the studies. 
Evidence of extensive host specialization of some of the smuts 
has been obtained. The existence of these races naturally com- 
plicates the problem of securing disease-resistant varieties. The 
progeny of various crosses between susceptible -and_ resistant 
