148 THE AMERICAN MONTHLY [May 



forms, formerly, and to some extent still, classified under 

 the order Hyphomycetes, in allusion to the great devel- 

 opment of their hyphae or thread-like vegetative system, 

 and with them were ranged in older works most of the 

 Peronosporese. Many of the Hyphomycetes are now 

 known to be forms in the life-cycle o( higher fungi of 

 the ascomycetous order, but for those whose develop- 

 ment has not been as yet certainly traced out it is still a 

 convenient resting place. The black moulds or Dematiei 

 occur mostly on dead wood and stems; Mucedines (white 

 moulds) on almost every conceivable organic substance, 

 such as leaves, herbaceous stems, jam, fruit, bread, paste, 

 leather, etc. In both series we usually find an abundant 

 mycelium, light or dark colored as the case may be, from 

 which arise the fertile hyphse, bearing the conidia, as this 

 type of spore is commonly called. The manner in which 

 these conidia are arranged largely determines the genus 

 and species of the individual under consideration. Thus 

 we may have them in tassels as in Penicillium (blue 

 moulds) when the hyplia divides somewhat palmately 

 prior to the formation of the conidia, and also in Asper- 

 gillus when the hypha ends in a swollen portion which 

 bears the conidia. They are borne on irregular branches 

 in Botrytis and Polyactis ; in tufts arranged in a race- 

 mose fashion in Botryo sporium, a beautiful snow-white 

 mould, common on decaying herbaceous stems. In all 

 these they are more or less globose and unilocular, but 

 they are pear-shaped and septate in Dactylium, very long 

 and with many transverse septa in Helminthosporium, 

 while in Macrosporium they are septate both longitudin- 

 ally and transversely, giving rise to the structure known 

 as "muricate." In fact, the variations are almost end- 

 less, and it is very difficult to convey an accurate idea of 

 tbeir structure by words without figures. 



Another group, also popularly called moulds and which 

 grow in similar situations, and very often on dung,are the 



