112 C. D. Sherbakoff 



maeroconidia, and both sometimes are of a very diverse type even within 

 themselves. (See F. diver sisy or urn.) 



2. Conidiophores often vary from mere minute projections on the side 

 of a hyphal thread to a complex dendroid structure often of a size observable 

 macroscopically. 



3. In the Fusaria for which production of sporodochia, plectenchymic 

 stromata, or sclerotia is typical, it sometimes happens that they are not 

 p oduced even under apparently favorable conditions. These structures 

 may vary in size, number, and form. 



4. The presence or absence of color is an especially variable character. 

 Changes in type of color may occur, but such changes are only apparent 

 and in all known cases can be explained on the basis of the difference 

 in the reaction of the medium (certain orange-red colors in acid become 

 blue in an alkaline medium), or, when a typical color is a compound one, 

 the change may be due to the preponderance of one or another of its 

 elementary colors. 



5. Extent of the development of aerial mycelium, zonation, rate of 

 growth, and character of the margin of the colony, may also vary to a 

 considerable extent. 



6. Especially great variation may take place in the relative production 

 of the different types of conidia and chlamydospores. 



It might appear at first glance that the variation of these fungi is so 

 great as to leave no firm ground for morphological treatment of the group. 

 And yet the actual situation is far from being so hopeless. First of all, 

 the great majority of the variations mentioned above occur, as did those 

 observed by Smith and Swingle (1904:59), under different environmental 

 conditions; while the variability under identical conditions usually (see 

 also Lewis 1913:225) is very slight. Secondly, the cases of variability 

 cited above are primarily cases of variation between presence and absence 

 of certain characters — which is, after all, of no great importance, because 

 when a certain character is present it is always peculiar to a specific type 

 of organism and thus this organism can be separated from others. Then 

 there are certain Fusaria which under almost any but extreme environ- 

 mental condition remain nearly the same throughout (as F. udum var. 

 Solani and F. cuneiforme). And finally, the most important character 

 in the classification of these fungi — the type and the shape of the conidia 



