DEUTEROMYCETES 



385 



There remain, however, some thousands of forms that 

 as yet have not been connected with any of the higher 

 species, and, as previously stated, it is the business of the 

 systematist to carefully describe and tabulate such so that 

 they can be recognised. 



Tulasne was the first to clearly indicate that various 

 forms of fruit were produced by the same fungus at 

 different periods of its development; this discovery was 

 the outcome of observing the constant sequence of forms 

 originating from the same mycelium or stroma. The 

 method of growing one phase of a fungus from the spores 

 produced by another phase has in some instances corro- 

 borated Tulasne's observations. 



From an economic aspect the Deuteromycetes are of 

 primary importance, as nearly all plant and animal diseases 

 caused by fungi are primarily due to infection by the 

 conidial form of fruit. 



There is a total absence of sexuality in the present 

 order, and all the varied forms of reproductive bodies 

 produced are truly conidia, although in systematic works 

 spores and conidia are often used indiscriminately. 



The forms are almost invariably minute, although owing 

 to the gregarious habit of many kinds, large and con- 

 spicuous patches are produced which are often brightly 

 coloured. 



The order is divided into three sub-orders, Sphaerop- 

 sidiaceae, Melanconiaceae, and Hyphomycetaceae. In 

 the Sphaeropsidiaceae the fruit is angiocarpous ; that is, 

 the conidia are produced in a definite perithecium as in 

 the Sphaerieae, but there are no asci, the conidia being 

 produced at the tips of simple or branched conidiophores, 

 which originate from the inner cells forming the wall of 



2 B 



