246 INTRODUCTION TO CRYPTOGAMIC BOTANY.. 



portant series, and afford excellent characters for distinguish- 

 ing analogous forms, but they are not so strict as might at 

 first sight be supposed, because, in addition to the normal mode 

 of fructification, there is another medium of propagation, by 

 means of cells separated as in the first case, from the tips of 

 filaments or their branchlets. These are what Fries has called 

 conidia, and there are few groups of Fungi in which they have 

 not been observed. In consequence, the same species may in 

 its different stages of growth be referred to perfectly distinct 

 orders : the common Hypoxylon deustum may, for instance, 

 be taken for a ThelepJiora, or an Erysiphe for an Oidium 

 (Fig. 20). 



237. But besides these bodies, which are evidently supple- 

 mental or analogous to the reproductive buds of Achimenes 

 or Lilium, there are others, which have at present not been 

 observed to germinate, or only imperfectly, and which 

 there is reason to believe are either spermatozoids or their 

 analogues. The bodies, like the spores themselves, appear 

 under two types, being produced at the tips of certain threads 

 or within vesicles. In the latter case, however, occasionally, 

 as in Trichothecium roseum* it is from the tip of the thread 

 or columella within the vesicle that they are generated. In 

 Nectria inaurata, Berk, and Br.,-f- however, the same hyme- 

 nium produces ordinary octosporous asci, and others filled with 

 a multitude of far more minute bodies, which are in all proba- 

 bility spermatozoids or their analogues. At present, these 

 bodies have been observed in comparatively few genera, but 

 the subject has not commanded attention till very*recently, 

 and is receiving every day fresh light from the researches of 

 M. Tulasne. No better example can be given than that of 

 Erysiphe, for we have there the true ascosporous sporangia, 

 the conidia on the threads of the mycelium and the pycnidia, 

 with their spermatoids or spermatozoids, if such they may be 

 called. The connection between the Oidium and Erysij^he, 

 is proved beyond all doubt, though it does not follow, as a 



* Hoffman iu Bot. Zeit., vol. 12, p. 249. 

 I See Gartl. Chrou , 1854, p. 470. 



