274 



THE AMEIUCAX NATURALIST 



[Vol. XLII 



way. Xow, what I mean is the kind of work which was 

 reported in the botanical session this morning on 

 PenicilHum and its relation to definite culture media, 

 and I believe in the very near future we shall be describ- 

 ing species, of many of these fungi in a definite relation 

 to culture media. A species will be a group of those 

 organisms which show a certain combination of morpho- 

 logical characters when grown upon a medium of definite 

 and known composition. The type of the species in- 

 volves a type medium* and the fluctuating variations 

 must be determined by the use of a series of such media. 

 Considerable work in this direction has been done, but 

 the method has not yet been well adapted to taxonomic 

 description. I think we are ready now to do this work 

 from a strictly taxonomic point of view. That will be 

 doing exactly what at least four of the speakers have 

 advocated, but they did not tell us in detail how to do it. 

 These fungi are particularly suited to this kind of work 

 for several reasons. In the first place, they are small 

 in size and we do not need a garden in which to grow 

 them; we can grow them in a test-tube. In the second 

 place, they reproduce exceedingly rapidly and we do not 

 have to wait a year or ten years in order to get them to 

 produce new generations. They may do that in a few 

 hours, or at most in a few days, so that we can produce 

 generation after generation, while the man who is work- 

 ing with flowering plants is waiting for one generation 

 to develop. Hence these plants are favorable material 

 with which to begin the kind of work which seems to be 

 demanded, namely, the union of the morphological and 

 physiological factors in the description and delimitation 



Mr. T. J. Burrill: I do not know that I have anything 

 very definite to say, but I am somewhat conscious of a 

 feeling that I am glad that I am not a taxonomist this 



