294 Morphologie etc. — Varietäten etc. — Physiologie. 



three potentially antheridial cells are cut off from the primary cell; 

 one of these divides to form a spermatogenous and a sterile cell; 

 the others, when formed, are more or less evanescent. Occasionally 

 there are two functioning antheridial cells, resulting in a bianthe- 

 ridial gametophyte. Jongmans. 



Burlingame, L. L., The origin and relationships of the 

 Araucarians. (The Bot. Gazette. LX. p. 1 — 26, 89—114. 1915.) 



The object of this paper is to attempt to set forth the principal 

 Views regarding the origin and relationships of the Araucarians, 

 and to Show on what sort of evidence each rests. The opinions 

 regarding the origin of the Araucarians may be grouped under 

 three heads: the lycopod theory, the cordaitean theory and the 

 abietinean theory. 



At the end of the paper the author gives the following summary 

 of the conclusions of his critical work. 



The science of phylogeny possesses fairly adequate and reason- 

 ably trustworthy rules of evidence. 



The degree of relationship is most clearly indicated by a de- 

 tailed and accurate comparison of all the structures of the plant in 

 all the stages of development, and is roughly proportional to the 

 number and exactness of the resemblances. 



Conclusions derived from direct comparisons should be checked 

 carefully by the geological record. 



Direct comparisons may be supplemented by indirect compari- 

 sons instituted through the use of more or less valid conclusions 

 derived from the presence of supposed vestigial structures in primi- 

 tive regions and from recapitulationary phenomena. Such indirect 

 comparisons afford much less certain conclusions. 



Reversions to ancestral conditions may sometimes occur under 

 normal conditions or be experimentally produced by wounding or 

 unusual conditions of growth. Conclusions based on evidence of 

 this sort have little weight unless supported by other more reliable 

 sorts of evidence. 



Gymnosperms as a group resemble one another much more 

 closely in very many ways than any one of them resembles any 

 other group. They are, therefore, monophyletic. Since the cycado- 

 phytes are almost certainly derived from a filicinean ancestry, it 

 follows that all are ultimately traceable to the same source. 



The conifers closely resemble Cordaitales and are probably 

 derived from them. 



Araucarineae resemble the Cordaitales far more closely than do 

 any other conifers, and are probably derived from them. This con- 

 clusion is consistent with the geological record, 



The transitional conifers of the Mesozoic are either araucarians 

 or cordaiteans well on their way toward Pinaceae. Some of them 

 may be actually ancestral to such Taxodineae as Cryptomeria and 

 Sequoia. 



The Abietineae are very old and are derived either directly 

 from the Cordaitales or from the very ancient members of the 

 Araucarineae. Jongmans. 



Harvey, E. M., Some effects of ethylene on the metabo- 

 lism of plants. (The Bot. Gazette. LX. p. 193-214. 2 Fig. 1915.) 



These investigations were undertaken with the object of deter- 



