Febbuaet 7, 1908] 



SCIENCE 



213 



destructive the past two seasons and to 

 which 85 to 90 per cent, of the rot was 

 due is a species of Diplodia, very probably 

 D. maydis. 



When an early infection takes place this 

 fungus causes a premature ripening and 

 shriveling of the ear, which usually remains 

 in an upright position with tightly clinging 

 and dark-colored husks. Later infections 

 Avhicli produce various degrees of rot in 

 the ear may or may not present the symp- 

 toms mentioned above; in fact, in many 

 cases the disease is not detected until 

 the husk has been removed. The seasonal 

 infections are started by conidia blown 

 from the old rotten ears and the one- 

 or two-year-old stalks left standing in the 

 field. 



A form of disease which is not uncom- 

 mon this season and due to a species of 

 Fusarium is recognized in that it is usually 

 more localized than that caused by Bip- 

 lodia affecting the ears in patches. The 

 fungus produces dense masses of mycelium 

 both on the diseased areas of the corn and 

 in pure culture. Microconidia are usually 

 found in abundance, while macroconidia 

 are rare. 



A third form of the rot noticed for the 

 first time this season is very characteristic 

 in that infection, with few exceptions, takes 

 place at the tip of the ear and the mycelium 

 soon develops a deep pink color. The fun- 

 gus thus far has proven to be sterile. The 

 effect on the corn is much the same as that 

 produced by the later infections of Dip- 

 lodia. 



Other forms of rot have been found to 

 be due to other species of Fusarium, and 

 one to one or more species of bacilli. 



From data collected from fifty or more 

 counties in Illinois in 1906, it is estimated 

 that more than 15,000,000 bushels of corn 

 having a value of $5,400,000 were destroyed 

 by rot. 



The Relation of "Conjugation" and "Nu- 

 clear Migration" in the Busts: E. W. 

 Olive. 



The seemingly conflicting results obtained 

 by Blackman and Christman in their in- 

 vestigations of the sexual phenomena in 

 the Cwoma type of rusts are to some extent 

 brought into harmony by certain new and 

 supplementary facts recorded in the pres- 

 ent paper. 



In the several species of Crnoma rusts 

 studied by the writer, fertilization was 

 found to be accomplished, much as Christ- 

 man maintains, through the absorption of 

 a portion of the walls of two essentially 

 similar gametes. The fusion process may 

 begin, however, through a very small con- 

 jugation pore, so that as the one protoplast 

 moves through the narrow opening to fuse 

 with the adjoining gamete, the nucleus may 

 thus sometimes be stretched out or con- 

 stricted, in this condition presenting an 

 appearance quite similar to that which 

 Blackman has termed "nticlear migration." 

 Siich an instance is regarded simply as a 

 case of conjugation between two cells in 

 which the connecting pore is as yet small. 

 The writer observed instances in wliich a 

 Blackman type of conjugation, as it may 

 be termed, through a narrow pore, occurred 

 side by side with a Christman type of 

 fusion, through a broad pore. The essen- 

 tial feature of the process is therefore 

 regarded as the equal participation of two 

 morphologically equivalent cells to form 

 the binucleated "fusion cell." 



But although the conclusions of Christ- 

 man are thus in greater part confirmed, 

 several observations made in connection 

 with the sexual fusions point to the impor- 

 tant conclusion that the two gametes differ 

 somewhat in time of development. The 

 observations on which this conclusion is 

 based are as follows: (1) In the Caoma 

 forms the first hyphse to push up under the 

 epidermis mass themselves often more or 



