54 Forest Club Annual 



obtained in artificial cultures in nine days from the date of cul- 

 turing. Two rather peculiar phenomena are exhibited by the 

 fungus when growing in artificial culture. The conidia are not 

 emitted from the pycnidia in ''spore horns" but they collect on 

 top of the pycnidia in small globules. Due to the great humidity 

 occurring within the culture, the conidia, as they emerge from 

 the ruptured pycnidium, do not coalesce to form the "spore 

 horn" ; but, after the mucilaginous coating of each conidium has 

 been softened by the absorption of moisture, they form a trans- 

 lucent gelatinous mass usually taking the form of a globule. The 

 other phenomenon is that the fungus has never been known to 

 produce the perfect or sexual stage in artificial culture. The 

 theory is sometimes advanced that certain food materials requi- 

 site to the formation of the perithecial stage are absent from the 

 artificial culture. 



Since a longer period is required for the maturation of the 

 ascospore stage than for the conidial and the growth of the fun- 

 gus is stimulated in artificial culture, it is, according to the more 

 prevalent theory, incited to fructification by the most direct route. 



It was found that, when the ascospores began to germinate, 

 the germinating tube protruded from either one or both cells 

 of the bicellular ascospores. The amount of swelling varied 

 with the different media in which the spores germinated. 

 When germinated in water they measured 14 by 7 microns, but 

 in a concoction of chestnut juice to which tannic acid had been 

 added they swelled before germinating to 17.5 by 10.5 microns. 

 The ungerminated spores measured on an average 8.75 by 4.3 

 microns. In pure chestnut extract they swelled before germina- 

 tion to 12.2 by 4 microns. Ascospores germinated in three days 

 at a temperature of 20 C. when in artificial culture. The con- 

 idia showed the same general phenomenon of swelling more be- 

 fore germinating when tannic acid was present. 



In the laboratory the spores of the chestnut blight fungus 

 have been found to germinate and the fungus to grow on and 

 in almost any medium ; such as, a decoction of chestnut bark, 

 twigs and leaves, corn meal, potatoes, beans, bullion, stewed 

 oak, in tannic acid, in 1 per cent glucose, on bread, and in rice 

 broth. The mycelium usually grows on the surface of a 1 per 

 cent glucose, solution. In this case, due to the distance at which 

 the mycelium was growing from the surface of the solution, the 

 supply of oxygen was limited ; most of it possibly being furnish- 

 ed by the glucose in the chemical changes induced in it bv the 

 presence of the fungus. 



Fulton (8) found that conidia germinate best at a tern- 



