606 SUMMARY OF CURRENT RESEARCHES RELATING TO 



him in the same periodical four years previously. It is remarkable for 

 the apparent absence of the sterile lamina, while the fertile spike is well 

 developed. This may be attributed to the presence of mycorhiza, which 

 facilitates the nutrition of the large spike in the dense wet forest, though 

 the sterile assimilatory lamina is absent. He has received further 

 Sumatran specimens from E. Rosenstock, and these possess a more or Less 

 pronounced outgrowth, which clearly represents a sterile lamina, thus 

 linking the species closer with 0. intermedium, and 0. pendulum, and 

 justifying the view that 0. simplex is a reduced and not a primitive 

 form. He adduces other anatomical reasons for rebutting D. H. 

 Campbell's views that the plant is a primitive form. 



Production of Dwarf Male Prothalli in Sporangia of Todea.* — 

 L. A. Boodle, when examining sporangia of filmy species of Todea (T. 

 FraseridbDA T. hymmophylloides), found antheridia in some of the closed 

 sporangia, and gives an account of his observations. When plants of 

 T. Fraseri are kept in a sufficiently damp atmosphere, sporangia do not 

 dehisce, and a number of spores germinate in situ ; among the simple 

 few-celled prothalli produced being some that bear a single terminal 

 antheridium. Similar iutrasporangial germination takes place in de- 

 tached sporangia if kept moist, antheridia being produced after three 

 weeks. The prothalli do not burst the sporangial wall, but die. Free 

 spores, placed under the same conditions as the sporangia, never pro- 

 duced dwarf male prothalli, but formed normal prothalli, which within 

 the limits of the author's experiments never produced sexual organs. In 

 T. hymmophylloides the spores germinate less readily, antheridiferous 

 prothalli being found in closed sporangia in only one or two experiments. 

 The formation of dwarf male prothalli in the sporangium is possibly 

 due to the concentration of certain organic food substances, caused by 

 pressure of the growing spores in the confined space. The concentration 

 may lead to special nutrition of the protoplasm, resulting in precocious 

 formation of sexual organs. 



Water-storing Tubers of Nephrolepis.f — J. W. Harshberger gives 

 a resume of what has been written by Yelenovsky, Heinricher, and 

 others, about the tubers of various species of Nephrolepis and their 

 function. He has himself investigated the tubers of two species, N. 

 cordifolia and N. davallioides, and finds himself somewhat at variance 

 with previous writers. The principal function of the tubers can definitely 

 be stated to be water storage, and the amount of water stored is consider- 

 able. The tubers aid the plant in tiding over the periods of drought. 



North American Pteridophyta. — A. H.TrundyJ describes the method 

 of growth of Lycopodium sabincefolium in Maine, where it occurs in large 

 circles (up to 150 ft. in circumference), ever growing outwards, the 

 younger plants being situated on the outside margin of the belt, and 

 the fruiting plants on the inside margin. The space within the circle 

 is covered with Cladonia rangiferina. A similar circular manner of 

 growth is noticeable in L. inundatum. 



o 



* Ann. of Bot., xxii. (1908) pp. 231-43 (1 pi.), 

 t Bull. Torrey Bot. Club xxxv. (1908) pp. 271-6. 

 t Fern Bulletin, xv. (1907) pp 70-1. 



