ZOOLOGY AND BOTANY, MIUKOSCOPY. ETC. 291 



male nucleus. It divides before the oospore and forms abundant 

 endosperm, but the cells immediately surrounding the embryo are devoid 

 of starch for some time. The ripe seed has a poorly developed suspensor 

 embedded in a globular mass of cells, and a thin seed-coat. At germina- 

 tion the cotyledons remain embedded in the endosperm until all the 

 starch is exhausted, when they assume their usual functions. S. G. 



CRYPTOGAMS. 



Pteridophyta. 



Size, a Neglected Factor in Stelar Morphology. — F. 0. Bower 

 {Froc. Boy. Soc. Edinhiirgh, 1920, 41, 1-25, figs.). An address upon 

 the correlation that may be observed between the size of a plant and its 

 internal structure. The relation of surface to bulk is discussed and the 

 effect which this would have upon the diffusion of gases and salts. The 

 endodermis is a living barrier placed between the stele and the surround- 

 ing tissues, and controls the diffusion of gases and solutions between 

 the outer tissues and the conducting system. The case of protostelic 

 ferns is first considered ; and it is shown how with increasing size the 

 cylindric stele becomes more and more deeply fluted, the area of the- 

 endodermis being thereby immensely extended. The solenostely, poly- 

 cycly, perforation, and dictyostely of the Leptosporangiate ferns are 

 then discussed ; the breaking up of the vascular tracts into meristeles, 

 each surrounded by its endodermis, leads to free communication between 

 cortex and medulla, and increases the proportion of endodermal surface. 

 Other instances are found in the tubers of Nephrolepis and Equisetum, 

 in the stipes and the root of ferns, in Selaginella, in the large prop- 

 roots of certain palms, in small Monocotyledonous stems. In plants 

 which possess secondary thickening, such as the Dicotyledons and 

 Gymnosperms, the endodermis soon becomes disorganized under the 

 stress of the growing cambium. It is suggested that by examining 

 the sheaths which surround the vascular tracts, their presence or 

 absence, their structure and permeability, and their approximate relations 

 to size, a better understanding of the vascular systems of plants, aiid 

 especially of the ferns, will be arrived at than by the most carefully 

 drawn comparisons of mere formal anatomy. Size must be considered 

 not only from the point of view of strength and external form, but also 

 from its tendency to modify internal structure and disposition of 

 tissues. A. Gepp. 



G-rouping and Mutation in Botrychium. — Charles J. Chamber- 

 lain {Bot. Gaz., 1920, 70, 387-98, figs.). A discussion of the status 

 of Botrychium dissectum. While in Ophioglossum there is abundant 

 Vegetative propagation by branching of the rhizome, this is not the 

 case in Botrychium \ for in Botrychium reproduction is by means of 

 spores and prothallia of the subterranean tuberous type which need to. 

 be associated with an endophytic fungus. The plants always occur in 

 groups, and such groups have l:)een carefully studied and plotted on 

 charts for some years by the author. Plants of B. viryinianum are 



