MICHIGAN ACADEMY OF SCIENCE. 37 



THE CULTURE OF FERN PROTHALLIA. 



[Abstract.] 

 Elizabeth D. Wuist. 



1. Excellent cultures of fern prothallia Avere obtained in porous pots by 

 keeping cultures in bright light and carefully regulating transpiration. 

 The majority of these prothallia were dioecious. Some were monoecious. 

 Prothallia bearing archegonia were made monoecious Ijy placing them in 

 a nutritive solution for a period varying from four to seven days. 



2. Spores germinated readily in water in bright Hght and when transferred 

 to nutritive solutions continued to grow and produced- normal functional 

 antheridia and archegonia on dioecious prothallia. Young sporophytes 

 produced, continued to groAv in the nutritive solutions. 



3. Spores did not germinate as readily in the nutritive solutions as in 

 water upon exposure to l)right light. 



THE FLORISTIC COMPOSITION OF THE VASCULAR FLORA OF 



MOUNT KTAADN. MAINE. 



LeRoy H. Harvey. 



To the plant ecologist alpine floras have an ever inviting interest, nor do 

 they furnish a less attractive prol)lem to the phytogeographer. Surrounded 

 by a lowland sea of unlike s])ecies they rise as volcanic islands of isolated 

 forms. This striking discontinuity in distribution and a partial floristic 

 agreement with other isolated peaks and the arctics early invited investiga- 

 tion. The first adec^uate solution of this interesting- problem was advanced 

 in 1856 by Dr. Asa Gray (4. 5, 6) in his glacial relict theory and subsequently 

 elaborated and extended l)y Hooker (9) and others. In an earlier treatment 

 of the origin of the Ktaadn flora (8) this theory was applied in detail to the 

 genesis of the plant societies of that peak. No detailed analysis of its 

 composition was published at that time, atterition being paid only to the 

 general effect of glaciatibn and recession upon the mass movements of this 

 alpine flora. To take up the latter phase of the problem is the purpose of 

 this paper. 



So firmly has the relict theory become established as the solution of this 

 phenomena that we fail in appreciating that any high mountain flora is 

 usually a composite of at least four distinct elements. If we consider only 

 the higher altitudes of the mountain the flora is dominantly composed of 

 arctic-relict species with which occur a possible few preglacial alpine forms 

 and a very limited number of endemic elements. The consideration of the 

 mountain in its entirety, however, demands the recognition of a fourth 

 element in the lowland forms which occupy its ravines and advance up its 

 most mesophj'tic slopes. Thus we come to designate these four elements 



