1909] CURRENT LITERATURE 477 



flowers; the number of stigma lobes; the length of style, hypanthium, and ovary; 

 length of main stem; number of side branches, etc. A large number of interest- 

 ing data of variability are here brought together. It is of interest that in nearly 

 all cases the modal number of stigma lobes shows a decrease from 6 or 8 or more 



to 4 during the season. 



The work is an extension of Shull's 10 statistical studies. Shull found that 



Lamarck 



forms 



more variable than the phylogenetically older. This appears to hold for the 

 European O. biennis and its mutants criiciata and suljitrea, but is only partly true 

 for O. Lamarckiana and its mutants. O. gigas and O. rubrineruis lata are more 

 variable than the parent in all the organs examined; but the other mutants are 

 more variable in some characters and less so in others. The coefficient of vari- 

 ability of a mutable species is not markedly different from that of a non-mutable 

 form. — R. R. Gates. 



Ontogenetic theory of alternation.— Lang 20 has outlined an interesting 

 theory of alternation of generations which he calls an "ontogenetic" theory, to 

 distinguish it from other theories. The so-called "homologous" and "antithetic" 

 theories are well known, and Lang's work on apogamy in ferns inclined him to 

 accept the former. In fact, the ontogenetic theory is a theory of homologous 

 alternation in its phylogcnetic application. 



The author starts with the idea that all the cell progeny of a germ cell are 

 potentially similar, and that any one of them might reproduce the organism. 

 The development of a specific organism is regarded as due to the properties of the 

 germ cell and to the conditions under which the germ cell develops. The author, 

 therefore, reaches the conception of a specific cell corresponding to each specific 

 form, to which under normal conditions it gives rise. In plants with a definite 

 alternation of generations, germ cells capable of developing into an organism are 

 met twice in the life-history. The organisms developed by these two cells may 

 be verv similar or very different. For example, in Polysiphonia the two resulting 

 organisms are very similar; while in bryophytes and pteridophytes they are very 

 different. To explain the latter case the author recognizes two alternative views: 

 (1) the two germ cells are so different that they necessarily produce different 

 structures; (2) the two germ cells are both specific cells of the same plant, but the 

 conditions of development are so different that the two resulting organisms are 

 very different. 



9 MacDougal, D. T., et al., Mutants and hybrids of the Oenotheras. Pub. No. 

 24, Carnegie Institution. 1 p. 57. fig*- '3- #*»• » *9°55 Mutations, variations and 

 relationships of the Oenotheras. Pub. No. 81, Carnegie Institution, pp. 92. &- 22. 



figs. 73. 1907. 



»o Lang, W. H., A theory of alternation of generations in archegoniate plants 

 based upon the ontogeny. New Phytol. 8:1-12. 1909. 



