l8 9! ] Current Literature. 349 



CURRENT LITERATURE. 



Minor Notices. 



Ever sinxe homologies were known to exist between heterosporous 

 pteridophytes and phanerogams the genus Isoetes has been one of 

 peculiar interest, for it has seemed of all known pteridophytes most 

 nearly related to phanerogams. Dr. Douglas H. Campbell, whose 

 •work in the life-histories of pteridophytes is well known, has made 

 a careful study of the life-history of a species of Isoetes ( I. echinospora, 

 var. Braunii), and has published his results in Annals of Botany (Vol. 

 V. no. 19, Aug. 1891), illustrated by three double plates. He has traced 

 the development of the male prothallium, the macrospore and female 

 prothallium, and the embryo as to its leaf, root, and foot). While the 

 details of technique are both interesting and instructive, for the sub- 

 ject was beset with unusual difficulties of manipulation, the interest 

 naturally centers about the conclusions with regard to the relationship 

 of Isoetes. The genus has been ordinarily placed among the Lyco- 

 podmeae, although Vines has called attention to its closer relationship 

 to Filicinese, to which latter view Campbell also inclines, and his re- 

 sults seem to bear him out in this view. However, Isoetes still seems 

 widely isolated at best, and its relationship to Filicinese, while nearer 

 than to any other pteridophyte group, may still be considered a some- 

 what distant one. While nearest to the Filicineae, it still seems to have 

 closer homologies with phanerogams than any other pteridophyte. 

 Campbell has succeeded in making the very important point that 

 these homologies are with the monocotyledons rather than with 

 the gymnosperms, thus emphasizing the notion of the independent 

 origin of the angiosperms from the pteridophytes and the further 

 notion of the origin of monocotyledons from the lilicine* through 

 such forms as Isoetes. Of course the intervals are still far too great 

 for definite conclusions, but these results with Isoetes are full of 

 suggestions for future investigations. 



The seventeenth contribution from the cryptogamic laboratory 

 of Harvard University is by William Albert Setchell, under the title 

 « Concerning the life-history of Saccorhiza dermatodea." It is are- 

 print from Proc. Am. Acad, xxvi., distributed September, 1891. It 

 deals with a very complex and polymorphous member of the l.aminar- 



Dealing first with its discover) by De la Pylaie, its distr.bution, 



habitat, and season, the author treats its morphology under four peri- 

 ods, each characterized by some important changes in deveh ment. 

 Then follows a complete account of the histology of each of these per- 



leae. 



