June IS, 1920 Relation of Rust in Seed Wheat to Seedling Infection 265 



EXPERIMENTS OP VARIOUS WORKERS 



A number of workers have grown plants from rusted seeds of various 

 kinds 'under various degrees of isolation. The results of these experi- 

 ments are rather variable. The writer has assembled the results and 

 the methods used in several of these experiments in Table II, which 

 includes the experiments of nine men conducted at different times in 

 different countries. None of these writers claimed to have secured 

 normal conditions for the growth of the host plants, and in no case was 

 any record taken of the atmospheric conditions inside the devices used 

 to secure isolation. 



Table II. — Summary of results obtained by other investigators in experiments on seed 



transmission of rusts 



« Reference is made to Linhart's work by Zukal (26); original work not published. 

 * Referred to by Jaczewski {14); original not seen" 



Eriksson carried on experiments for seven years and secured only a 

 very few infections upon plants grown inside his "isolation frame." 

 This frame was made of glass with wooden corner posts and an iron roof. 

 Ventilation was secured by drawing air through a cotton filter. At best 

 a cotton filter is not very satisfactory, and it is to be noted that Eriks- 

 son secured his positive results after the cages had been used three or 

 four years. Grove {ii, p. 45-47) makes an interesting comment upon 

 Eriksson's work. He says {p. 45) — 



on some of his "protected" plants aphides also made their appearance, yet this 

 does not seem to have suggested to him [Eriksson] that the zooplasm of the aphides 

 must also have been latent in the seed . If the aphides got in, so would fimgus spores, 

 since it has been proved that uredospores are carried by them and other insects. 



Klebahn repeated Eriksson's experiments and found one plant infec- 

 ted with Puccinia graminis in his glass cages. He explains this {16) by 

 the fact that this infection did not appear until a few days after he had 

 been working with P. graminis near this cage. The time which had 

 elapsed was about the normal incubation period for this rust. It seems 

 very likely, therefore, that the one infection noted originated from 

 spores accidentally introduced. 



