no MORPHOLOGY AND LIFE-HISTORY OF YEASTS. 



the same in each ascus, and not infrequently an odd number is 

 present. A similar lack of precision is also exhibited in other 

 genera, such as Ascoidea, Protomyces, and TlieJeholus. Brefeld 

 (IX.) would associate all these into a special group, to which he 

 gave the name Hemiasci, intending thereby to express the im- 

 perfect character of their asci, and that the development of the 

 latter from the sporangia had been, as it were, arrested half- 

 way. Therefore, according to his ideas, the Hemiasci formed a 

 connecting link between the sporangiogenic Phycomijcetes and 

 the true Ascomycetes. Brefeld then endeavoured to effect an 

 analogous separation between the other Myco)7iycefef<, which, 

 as we are aware, differ from the Aaroniyretes by lacking the 

 capacity for producing endogenous spores, and fructify by means 

 of conidia. In the highest of these, namely the Bai^idiomycetes, 

 the conidiophore is developed into a basidium (§ 384). On the 

 other hand, in a number of Mycomycetes that do not exhibit 

 ascofructification (viz. the UMaginetn and the TiUetiece), the 

 precision of the conidiophores is not so great as in the rest. 

 Consequently the}' were separated — under the name Hemi- 

 hasidii — from the latter, or Basidiomycetes ; and, according to 

 Brefeld's ideas, they formed an intermediate link between the 

 Phycomycetes group (with conidial fructification) and the Basidio- 

 mycetes. They therefore constituted a branch of the Hemiasci ; 

 and these latter were grouped by Brefeld along with the Hemi- 

 ba^idii, to form an intermediate kingdom, under the new name 

 of Mesomycefes. This conception, which is more fully detailed 

 in a work by F. von Tavel, and according to which the SaccJiaro- 

 mycetes should no longer be regarded as full-fledged Aaroniycetes, 

 was opposed by "W. Zopf ; but the final settlement of this highly 

 complex question has not yet been reached. For us the Sac- 

 i-liaromycete^ will still continue to rank with the Ascomycetes, 

 sub-class (order) GyDmoasceo', and not as Hemiasci. 



Any worker who attempts to trace a relationship between 

 the Saccharomyeetes and other fungi must agree with Ileess"s 

 classification of the foi'mer with the Ascomycefes. Neverthe- 

 less, there is still room for diversity of opinion within the above 

 limitation of the question. Thus, A. de Bary had already shown 

 the great agreement, in structnre and other particulars, between 

 the Sarrliaivmycetes and certain of the E.roascece, and remarked 

 that the former might at once be ascribed to this latter group. 

 Another matter worthy of attention is the question regarding 

 any eventual connection between the Saccharomycetes and cer- 

 tain Hyiiliomycefes which' have hitherto been included in the 

 group of Fumji imperfecti. Some warrant may be accorded to 

 such enterprise, though not without attention being drawn at 

 the same time to the circumstance that a successful result must 

 primai'ily be placed to the credit of these Hyphomycetes, since 

 they would thereby obtain recognition as forming part of the 



