114 C. D. Sherbakoff 



FORMS OF FRUCTIFICATION IN PURE CULTURES 



(Spores 

 The spores in the genus Fusarium are of two kinds: conidia, or acrog- 

 enous spores, and chlamydospores, or endogenous resting bodies. The 

 conidia in turn may be divided into two more or less distinct types: 



(1) macroconidia, sickle-shaped, three- or more septate spores; and 



(2) microconidia, oval, non- or only one- or two-septate spores. 



Before the appearance of Appel and Wollenweber's work (1910) the 

 existence of micro- and macroconidia as two distinct types was more 

 or less generally accepted, but in that work it was concluded (page 29) 

 that there is only one type of conidia. The latter view is, of course, 

 correct so far as the genetic relationship between micro- and macroconidia 

 goes. Nevertheless, the typical presence of microconidia in certain closely 

 related Fusaria and their typical absence in others is characteristic. 

 Besides, whenever they are present they have a comparatively constant 

 and often peculiar type of their own. Thus, they can be used as a good 

 natural basis for classification of these fungi, and for that reason must 

 be considered as a type separate from macroconidia. 



In this paper the term microconidia is applied to all nonseptate, and seldom 

 to one- and even to two- or three-septate, conidia of a different shape from 

 that of the macroconidia, which are sickle-shaped and usually three- or more 

 septate. Different forms of macroconidia are shown in figure 1 (page 112). 



Chlamydospores may be borne on the ends of special lateral branches 

 of the mycelium (terminal chlamydospores), or they may be intercalary. 

 They often are produced in the ends of the conidiophores, in the conidia 

 or in the ends of special branches from the conidia. The chlamydospores 

 are single, in short to long chains or in more or less large clusters. They 

 are of common, though not of general, occurrence, and in a number of 

 Fusaria both terminal and intercalary chlamydospores are present; in 

 some others there are only terminal, and in still others only intercalary 

 chlamydospores have been observed. A number of Fusaria evidently 

 have no true chlamydospores; they may possess structures with dense 

 content, but these structures are not thick, double-walled bodies. 



Forms of fructification 

 Sometimes, as in the case of the conidia on aerial mycelium of 

 F. trichothecioides, and also in the sporotrichial form of F. sporotrichioides, 



