Pteridophyten. — Floristik, Geographie, Systematik etc. 597 



Schaffner. J. H., An interesting Botrychhim habitat. (The 

 Ohio Nat. X. p. 8—9. 1910.) 



Notes on the occurrence of several species of Botrychium, in- 

 cluding two rather rare species,' B. simplex and B. neglectiim, on 

 Cedar Point, Erie County, Ohio, in an open thicket of Rhus 

 hirta and other small trees and shrubs. This is the first substantiated 

 record for B. simplex in Ohio. Maxon. 



Shattuek, C. H,, The origin of heterospory in Marsilia- 

 (Bot. Gaz. IL. p. 19—40. pl. 3—6. Jan. 1910.) 

 The author has artificially caused the production of large spores 

 in microsporangia, thus showing how heterospory has probably 

 arisen in this plant. It was found that the sporangia are very sen- 

 sitive to the inliuence of water and low temperature, especially at 

 the spore mother cell stage, and it was possible by using a spray 

 of water to kill the megaspores and then by putting the plant 

 under good conditions to cause some microspores of a sporangium 

 to enlarge at the expense of the rest, and show some or all of the 

 characters of megaspores. A contest for supremacy occurs in a 

 microsporangium, and several spores maj'- enlarge, but one finally 

 matures at the expense of the rest. Such enlarged microspores may 

 be eight to sixteen times as large as the ordinary ones. Thus stages 

 in the evolution of heterospory, such as are represented in Cala 

 mostachys, may be produced experimentally. M. A. Chrysler. 



Twiss, E. M., The prothallia of Aneimia and Lygodium. (Bot. 

 Gaz. IL. p. 168—181. pl. 10—11. March 1910.) 



The spores are tound to possess three distinct coats, exine 

 intine and epispore, laid down in the order named. In germination 

 the first cross-wall does not separate a rhizoid and first prothallial 

 cell, but the spore divides into two cells of unequal size, ttae smaller 

 of which gives rise to the rhizoid. This feature may be characteristic 

 of Schisaeaceae. The structure of the antheridia and archegonia is 

 the same as in Polypodiaceae. M. A. Chrysler. 



Hassler, E., Contribuciones ä la Flora del Chaco argen- 

 tino-paraguaye. Primera Parti. Florula pilcomayensis. 

 (Trabajos del Museo de Farmacologia de la Facultad de Ciencias 

 Medicas de Buenos Aires. 21. 154 pp. Buenos Aires, 1909.) 



La collection de Morong (1892) nous a fait connaitre 294 

 especes de plantes vasculaires de Pilcomayo Sud, celle de Gra- 

 ham-Kerr (1893) augmenta le nombre de 136 especes, c'est-ä-dire 

 en tout 430 especes signalees pour cette region. 



En 1906 Teodoro Rojas trouva 573 especes, dont 271 nou- 



velles pour la region du Pilcomayo et 16 nouvelles pour la science. 



L'^numeration de l'auteur comprend les 701 plantes vasculaires 



trouvees dans ces trois expeditions. II profite de l'occasion pour 



corriger les determinations erronees de Morong et Britton 



A. Gallardo (Buenos Aires). 



Pammel, L. H., Rocky Mountain Rambles. (Plant World. 

 XIII. p. 155-163, 181-190. July and Aug. 1910. f. f.) 



This paper illustrated with views of Rocky Mountain Vegeta- 

 tion gives a descriptive account of the different t5'^pes of plant 



