CURRENT LITERATURE. 95 



tissues or cells, as embyro sacs, tapetal cells, pollen tubes, etc. In 1915 Miss 

 Pramkherd drew attention to the frequent occurrence of such cells in differ- 

 ent tissues of young organs of widely different but by no means specialised 

 character. Among ferns they were found in the petiole and sporangioph- 

 ore ; among phanerogams in petiole, hypocotyl, coleoptile, stem, inflorescence 

 axis, plumule bud and pedunole. They tend to occur in regions of activity 

 and rapid elongation, and are due, she supposed, chiefly to amitotic division, 

 and being probably followed by wall-formation, might contribute to the rapid 

 formation of the tissue. Rudolf Beer and Agnes Arber in the paper now 

 under notice, record the occurrence of binucleate and multinucleate cells in 

 vegetative tissues of 177 species representing 60 families, most frequently in 

 the stem but also in roots, and always characteristic of young actively growing 

 tissues. In opposition to the majority of observers they consider that the 

 division of the nucleus has always been a mitotic one, no single instance of 

 direct division having been observed. A peculiarity in the development of 

 the binucleate condition is the formation of what the authors propose to call 

 the Phragmjspherc. After the spindle plate has made its appearance it is 

 apparently resorbed, and the whole phragmoplast with its associated cyto- 

 plasm becomes transformed into a hollow sphere which encloses the two 

 nuolei and ultimately becomes co-extensive with the cytoplasm lining the 

 cell-wall. 



The fate of the nuclei varies : in some cases they persist, even, as in the 

 cortex of Rosa, for two years. In some they soon degenerate ; but there is 

 no evidence of fusion. 



From the frequency of the occurrence of bi- nucleate and multinucleate 

 cells in growing tissues the authors regard them as a normal feature, a 

 definito phase in the growth of the higher plants. 



This phase usually succeeds the meristematic stage and preoeeds the 

 period of maximum growth and may therefore be considered as due to a loss 

 by the cytoplasm of the power to divide, while the nucleus is still capable of 

 doing so. The authors are inclined to think that the diffusion into the cyto- 

 plasm of the nuclear material both at each division (because of the solution 

 of the nuclear-membrane) and on the disintegration of the nuclei, may contri- 

 bute to the cj'toplasm and affect its activities. 



P. F. F. 



Hepaticae. 



Campbell D. H. Studies on some East Indian Hepaticae. Annals 

 of Botany Vol. XXII. No. CXXVII. July 1918. 



The writer describes the structure and development of some species of 

 Dumorticra and gives the description of a new monoecious species of the genus 

 from Borneo characterised by the formation of several (5-6) sessile successive 

 male and female receptacles on a series of terminal adventitious shoots. 

 The stucture of Wiesnerella denudata (Mitten) St, is also described. The 

 author concludes that D. velutina. shows the least reduction, for not only are 

 the outlines of the air-chambers quite evident, but the characteristic assimila- 

 tive tissue is present in the form of very numerous superficial papillate cells. 

 In D. trichocephalla, which is more strongly hygrophilous in habit, the reduc- 

 tion of the air-chambers is much more complete, and in a third species, from 

 Hawaii, probably D. hirsuta, the suppression is complete. 



