MO ULDS—H YPHOM YCE TES 



Fig. 129.— FcnicilUum 

 with the conidia iu 

 chams. 



a distinction is made between such conidia as are solitary and 

 those which are produced in chains, or catenulate (Fig. 129) ; 

 between those which are solitary and those which are clustered 

 at the apex of the hyphae, or its branches, 

 so as to form more or less dense heads, or 

 clusters of conidia ; between those in which 

 the conidia are terminal and those in which 

 they are lateral or dispersed. Other dis- 

 tinctions are derived from the hyphae them- 

 selves, whether simple or branched ; or if 

 simple, whether inflated at the apex or not ; 

 and if branched, whether simply furcate, 

 repeatedly divided, or if the branches are 

 arranged in whorls or verticillate. All 

 these are details which are readily gathered 

 from the diagnoses of the separate genera, 

 and we have said sufficient to indicate the 

 principal features which have to be taken 

 into account in the determination of the genus to which any 

 particular mould may belong. 



Although the above observations apply in the first instance 

 to the 31'ucedines, they apply also generally to the Dematieae, 

 with the exception that in the divisions based on the forms 

 of the spores, or conidia, there will be found an additional 

 division, the Dictyosporae, in which the conidia are divided in 

 both directions, so as to be clathrate or muriform. Some of 

 these conidia will therefore present the appearance of twenty 

 or more simple cells, aggregated into one large complex 

 conidium. Judging from the facility with which each cell of 

 these compound conidia germinates, it may be inferred that 

 each cell is a reproductive unit, and is in itself a perfect 

 conidium, capable of reproducing the species. So in respect 

 to uniseptate or multiseptate conidia, in a linear series, each 

 cell is capable of germination, and even, in some instances, of 

 separating itself from its sister cells, when arrived at maturity 

 (Fig. 130). Mr. Worthington Smith, in his observations on 

 Fusarium solani, has intimated that, although some of the 

 segments of the conidia germinate at once, others are capable of 

 undergoing a period of rest. He says, " Sometimes these little 



