408 BOTANICAL GAZETTE [MAY 
Studies of cambium.—BarLey,™ in continuation of his studies of cambium, 
has considered the size variations of cambial initials in Gymnosperms and 
Angiosperms, making an extensive reconnaissance through the representatives 
of these groups, tabulating measurements of 13 species of Gymnosperms an 
54 species of Dicotyledons. He finds striking variations in the dimensions of 
the cells of the cambium and secondary xylem, some of the variations being 
purely somatic, while others are germinal. He finds that in many plants 
the dimensions of tracheary cells are determined by those of the cambium 
initials, while in other plants the dimensions are due to changes during the 
differentiation of the xylem. He concludes that these fundamental types of 
size variations and the fluctuations in form and structure are significant in the 
investigation of certain cytological, morphological, and physiological problems. 
He calls attention to the fact that the cambium is an unusually favorable 
medium for the study of problems relating to cell size and body size, the work- 
ing sphere of the nucleus, the nucleocytoplasmic relation, and phenomena of 
cytokinesis in somatic tissues.—J. M. C. 
Morphology of Larix.—In a study of various stages in the life history of 
Larix leptolepis, Doyle's brings out some points of interest. His study of the 
cavities at the apex of the microsporophyll leads him to conclude that they 
are homologous with similar cavities in the vegetative leaves, and that they 
do not represent abortive sporangia. He also suggests that similar cavities 
in Ginkgo, Torreya, and other forms may have as little relation to a previous 
spore-producing function. The microspore, which is wingless, is shed with 
the stalk and body cells already formed, as in Abies. Some of the figures 
and the number of peculiar conditions are about what one might anticipate 
in a thorough study of almost any Gymnosperm. In the ovulate cone there 
is a gradual transition from vegetative leaves to cone bracts, as in Pseudotsuga. 
The general conclusion is that numerous similarities indicate a distinct natural 
affinity between Larix and Pseudotsuga.—C. J. CHAMBERLAIN 
North American Flora.—Parts 5 and 6 of volume 7 include a lig asst 
of Aecidiaceae by ARTHUR and his colleagues, chiefly the genus Dicaeoma 
under which 269 species are recognized. The following genera are also in- 
cluded: Pucciniola (25 spp.), Allodus (49 spp.), and Klebahnia (8 spp-).— 
}, Mek. 
4 Bartey, I. W., The cambium and its derivative tissues. II. Size variations 
of cambial initials in Gymnosperms and Angiosperms. Amer. Jour. Bot. 7:355-307- 
figs. 3. 1920. 
5 Doytz, J. D., Observations on the morphology of Larix leptolepis. Sci. Proc. 
Roy. Dublin Soc. 15:310~-330. pls. 17, 18. 1918. 
