84 



THE AMERICAN BOTANIST 



phora" as an algal specimen, and "Marchantia'' as an all-suffi- 

 cient exemplification of a liverwort are gone, we trust forever ; 

 and the large variety of genera and species offered by the bio- 

 logical supply houses today renders a defense of the haphazard 

 choice of illustrative types both futile and needless. 



To be specific: we desire to have specimens that will (1) 

 adequately represent the groups, without undue specialization. 

 — ''central types"; (2) offer a progressive sequence in phy- 

 siology and morphology without sacrifice of natural relation- 

 ships; and (3) picture the main lines and data of phylogenetic 

 history, and do this without, implying precarious genealogical 

 hypotheses. 



Now it is just this list of desiderata that the ''orthodox" 

 t3^pes, as we might almost dub them, fail to satisfy. To begin 

 with, we wish an exceedingly primitive, isolate, holophytic cell 

 with which to commence the Thallophytes (I include here the 

 Protophytes) , and what do we find proposed ? Plenrococcus, — 

 or worse, Oscillatoria. The first is already triply specialized 

 beyond the imperatively simple structure of a primordial type; 

 for it possesses a nucleus, chromoplasts, and a cellulose wall; 

 and the second is an even more fraudulent substitute for the 

 thallophytic "precurseur". it is even filamentous! 



Again, take the Chlorophyceae : why pick the bizarre Sphae- 

 rella as a type in place of the ideally unspecialized Chlamydo- 

 monas? And why on earth suggest even Pandorina or Volvoxf 

 Can we get "to an3^where" in botany by following the morula- 

 blastula road so clearly indicated in these organisms? And 

 why present the Zyg-ophycean cul-de-sac to the bewilderment 

 of the neophyte? Such groups lead tO' nothing and profit the 

 student not one idea, except a trifle of curious data in algology. 

 What is the use, moreover, of introducing the unusual and 

 never-to-be-met-with-again problem of coenocyt.ism in Vaiiclr 

 eria — unless it is at once followed up by the treatment of the 



