BOOKS AND CUKRENT LITERATURE 193 



tion that in spite of the several critical researches of Ward and the more 

 recent ones of Zach and Beauverie, Eriksson still appears in defense of 

 his hypothesis. Pritchard finds that rust-infected wheat grains con- 

 tain living mycelium within the tissues of the pericarp adjacent to 

 rust sori. The mycelium resumes its activity with the growth of the 

 seedling, in case such infected grains are planted. The fungus pene- 

 trates the tissues of the young plant, growing also in the spaces between 

 the leaf sheaths. The formation of new uredo sori from this mycelium 

 has not been observed. When rigorous measures were used to exclude 

 the possibility of external infection, rust-free plants were obtained on 

 sowing rust-infected seed. Wheat sown at various dates remained 

 nearly free from rust until it began to head, in spite of repeated attempts 

 at inoculation. It is plainly evident that the fungus lives over winter 

 in certain wheat grains and that this is at least one very probable source 

 of infection. Whether after infection of the embryo there might not 

 be a time at which the mycelium becomes virulent, namely, when it 

 spreads to form pustules as is assumed in Eriksson's mycoplasm hypoth- 

 esis is at least a very interesting possibility. — Frederick A. Wolf. 



