Foe pe 
1907] CURRENT LITERATURE 231 
described a new genus (Pseudomachaerium) of Leguminosae (Dalbergieae) from 
Paraguay.—P. B. Kennepy (Muhlenbergia 3:8. 1907) has described a new Tri- 
folium from Montana.—T. D. A. CocKERELL (idem g) has published a new 
genus (Microbahia) founded on Syntrichopappus Lemmon.—A. A. HELLER 
(idem 10-12) has described new western species under Cakile and Ribes.—A. 
NELSON and P. B. Kennepy (Proc. Biol. Soc. Wash. 19: 35-40, 155-158. 1906) 
have described new species from Nevada under Eriogonum (2), Arabis, Ribes, 
Gilia, Phlox, Castilleia, Hulsea, Raillardella, Chrysothamnus, Sophia, Sphae- 
rostigma, Godetia, Oreocarya, Cryptanthe (3).—J. M. C. 
Ecology and taxonomy of Caulerpa.—SvEpELtus*4 has published the results 
of his studies of the Ceylonese species of Caulerpa. In a discussion of their mode 
of life the following subjects are presented: (1) ‘‘do all Caulerpas grow under 
similar external conditions ?”; (2) “different ecological types as distinguished by 
the varying development of ees root-system,” and (3) “‘of their assimilation 
in the following enumeration: (1) those which depend on locality, and which 
are to be considered adaptations or ‘‘ecologisms;”’ (2) those which cannot be 
considered as ecologisms, but are the result of fluctuating variability among the 
different branchlets; (3) those which can be considered as phylogenetic stages of 
evolution; (4) bud variations of atavistic origin; (5) dwarf forms; (6) those 
which do not fall under any of these categories and may be bud variations without 
atavistic origin (=mutations). 
In the taxonomic part of the paper twenty-one species are presented and 
illustrated, two of them being new.—J. M. C. 
Experiments on cell-formation.—By subjecting root tips to various ee 
factors, such as MgSO,, NaCl, benzine vapor, and extreme tempera 
NEmec°s finds that cell walls do not always appear between the daughter oe 
and that the daughter nuclei frequently fuse, the resulting nucleus of course having 
the double number of chromosomes. In the tips subjected to benzine vapor, 
the chromosomes are shorter and thicker than the normal ones, although in their 
formative stages no abnormalities can be observed. He was most successful with 
root tips of Vicia Faba, Galtonia candicans, Hyacinthus, and various euphorbias. 
Staminate branches of Larix decidua were placed in a warm chamber and sub- 
jected to the action of chloroform vapor. There was little doubt that some 
pollen mother cells passed directly over into pollen grains. Mixed among these 
pollen grains true tetrads were occasionally present. Sometimes the pollen mother 
cells divided once, giving rise to two pollen grains.—W. J. G. 
34 SVEDELIUS, Nits, Ecological and systematic studies of the Ceylon species of 
Caulerpa. Ceylon marine biological reports no. 4. pp. 81-144. figs. 51. 1906. 
3s NEmEc, B., Ueber die Bedeutung der Chromosomenzahl. Bull. Internat. 
Acad. Sci. Bohéme 10: pp. 4. 1906. 
