316 BOTANICAL GAZETTE [OCTOBER 
the earlier cycadophyte stock. Accordingly he introduces before ARBER and 
ParKIN’s ‘‘pro-anthostrobilus” an evolutionary stage characterized by the group- 
ing of filicinean microsporophylls and megasporophylls in monosporangiate 
strobili, and to this hypothetical stage he gives the name “‘pteridostrobilus.” 
This stage was temporarily a common one for the general cycad and angiosperm 
phyla; and at this stage the cycads practically stopped, with reduction of sporo- 
phylls; while the angiosperm phylum proceeded to the establishment of the 
bisporangiate condition, the evolution of angiospermy, the transformation of the 
habit of the vegetative body, etc. According to Licnrer, the Bennettitales 
represent a different phylum, which branched from the cycadophyte phylum 
after the angiosperms, but still at the pteridostrobilus stage—J. M. C. 
Nitrogen fixing bacteria.—In a short preliminary paper’? BREDEMANN sum- 
marizes the conclusions deduced from his study of nitrogen’ fixing bacteria of 
the Clostridium type. Eleven cultures of the so-called “species” of various 
authors were compared with sixteen types isolated by himself. These types 
were from many sources, particularly soil from different parts of the world. A 
comparison of these forms cultivated under proper conditions for considerable 
iods has convinced him that all must be considered as a single species, 4 
ethods, 
Most 
Saprolegniaceae. He has found it possible to isolate species of Sapro’ co 
ere used 1n 
substances 
de BREDEMANN, G., Regeneration der Fahigkeit zur Assimilation 
Stickstoff des Bacillus amylobacter A. M. et Bredemann und der zu dieser - Bak- 
gehérenden bisher als Granulobacter, Clostridium usw, bezeichnete anaeroben 
terien (Vorlaufige Mitteilung). Ber. Deutsch. Bot. Gesell. 26a: 362-368: 1908. 
2° Kaurrman, C. H.. A contribution to the i of the 
: + Ge physiology ig ant 
with special reference to the variations of the sexual organs. Annals of Botany 
361-388. pl. 23. 1908. 
