274 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Its size increases in proportion to its distance from the apes. He gives 

 a synopsis of the sis species esamined according to the method of apical 

 growth — main shoot, lateral shoots, fructification. In all Selaginellas 

 the lateral shoots arise quite laterally without any connesion with a leaf 

 rudiment. Later on, the leaf-base of a neighbouring leaf may become 

 so strongly developed that the shoot appears to be asillary. Another 

 synopsis is given which is based on the method of branching in the 

 species esamined. Species which grow by one initial cell branch mono- 

 podially ; others with more than one initial cell show true or modified 

 dichotomy. There are also intermediates which render it difficult to 

 determine the mode of branching. 



Prothallus of Equisetum debile.* — S. R. Kashyap gives an account 

 of the structure and development of the prothallus of Equisetum debile, 

 an Indian species. The prothallus is remarkable thus : — 1. Diversity 

 of methods of wall-formation in early stages. 2. Lobes always erect 

 and crowded in natural prothalli. 3. Radial symmetry of prothallus 

 from the earliest stages, -i. Large size when mature. 5. Effect of 

 light upon structure and colour of upper half — very compact and red in 

 direct sunlight ; spongy and green in shade. 6. Absence of purely 

 male prothalli. 7. Protogynous condition of the prothallus, helping in 

 cross-fertilization ; but all female prothalli do not produce antheridia. 

 8. Resemblance of antheridia to those of Lycopodium in position, struc- 

 ture, and paraphyses. 9. The archegonium has a single neck-canal cell, 

 another point of resemblance to Lycopodium cernuum. 



Mised Pith in Osmunda regalis.j— D. T. Gwynne-Vaughan gives 

 an account of the structure of an anomalous stem of Osmunda regcdis, 

 the pith of which at certain points contains scattered medullary tracheas. 

 He holds that this gives support to the theory that the pith of the 

 Osmundacese is phylogsnetically stelar and not cortical, and that it arose 

 by the progressive conversion of the central tracheae of a solid sylem 

 strand into parenchyma. 



Botrychium.t — I. Tidestrom discusses Botrychium virginianum and 

 its forms, including the earliest records in North America. He recognizes 

 two species — B. cicutarium (Savigny) Swartz, with persistent leaves and 

 sporophyll about equal to the sterile segment ; and B. virginianum 

 (L.) Swartz, with leaves not persistent and sporophyll long-esserted. 

 He regards B. brachystachys Kunze and B. dichronum Underw. as 

 synonyms of the former. 



Corynepteris and Zygopteris.§ — P. Bertrand publishes a note on 

 the relation of impression-fossils of Corynepteris to Zygopteris, the 



* Ann. of Bot., xxviii. (1914) pp. 163-81 (figs.). 



t Ann. of Bot., xxviii. (1914) pp. 351-4 (1 pi.). 



I Contrib. U.S. Nat. Herb. Washington, xvi. (1913) pp. 299-303 (1 pi.). 



§ Comptes Bendus, clviii. (1914) pp. 740-2. 



