THE AMERICAN BOTANIST 



branching filament. Aphanochaete (I admit a not very com- 

 mon genus) presents an ideal alga for the exemplification of 

 gamete-differentiation, together with the tendency toward con- 

 crescence of branches that eventually leads to the thalloid types. 

 The decided advantage of this genus in the presentation of 

 gamete-differentiation lies in the fact of its obvious and im- 

 mediate relationship with the preceding types and the succeed- 

 ing. Citations of Cutleria or Pandorina and Volvox are quite 

 beside the mark when such a satisfactory genus as Aphano- 

 chaete is available for the demonstration. Coleochactc sohita 

 serves as an excellent type for presenting the final differentia- 

 tion of the sex-cells and for the significant increase in size of 

 the fertilization-product, the sporocarp. C. scutata pictures the 

 transition of body-form from a concrescent filamentous struc- 

 ture tO' a leaf-like thallus. 



Right in this connection the problem of fungal origins is 

 to be best taken up — as far as the Phycomycetes are concerned ; 

 and it is well, pedagogically speaking, to utilize such vivid 

 transitional cases for the stimulus they offer to the student in 

 the direction of homologies and data of phylogenetic signifi- 

 cance. Bessey's consistent and courageous treatment of the 

 alga-like fungi in close (in fact immediate) relation with their 

 progenitors should have a more hearty assent, it seems to me, 

 than we have given it. And there is little difficulty in introduc- 

 ing the types through an ideal series. First the problem of 

 coenocytism is to be worked out in the algal ancestry : and for 

 this Cladofhora and Vauchcria serve excellently. In the latter, 

 the second problem, that of saproph3^tism, is raised and its 

 solution indicated in the occurrence of the ''rhizoids''. Sapro- 

 legnia next, with its incipient degeneration of the sexual 

 process, introduces the fungal types proper (the student might 

 well be referred here to the Phyllosiphonaceae) . Albugo and 

 Rhisopus, illustrate the further adaptation to aerial life and the 

 ultimate degeneration of gamete-differentiation. 



