504 BOTANICAL GAZETTE [ DECEMBER 
The same author has published? also a new rush from the Rocky mountain 
region, /uncus confusus, which has heretofore been confounded with /. ¢enuzs 
congestus Engelm. In the same connection a synopsis of /. ¢emuzs and its 
allies, seven species in all, is given. Professor E. L. Greene’s last fascicle of 
‘new or noteworthy species’’® contains descriptions of new species in the fol- 
lowing genera: Crategus, Mentzelia (2 sp.), Coleosanthus, Solidago (2 sp.), 
Chrysopsis, Grindelia (3 sp.), Aster, Arnica (4 sp.), and Senecio (4 sp.). 
Among the numerous new species which Mr. Hemsley has described? from 
an interesting collection received from central Tibet is a new genus of grasses 
which he has named Litt/edalea.—J. M. C. 
Dr. W. ARNOLD! has obtained some interesting results from his study of 
Isoetes and Selaginella.° The species used were 7. Malinverniana and S. 
cuspidata, and their association under the title indicates the author’s conclu- 
sion that Isoetes is to be regarded as a heterosporous lycopod. In the forma- 
tion of the prothallium of Isoetes the macrospore nucleus passes to the 
apex of the spore and divides, the daughter nuclei again dividing. At this 
time the arrangement and staining of the striations of protoplasm about the 
nuclei indicate that cell walls are about to be formed. The spore wall 
becomes double and walls are formed about the nuclei, usually leaving the 
nucleus unenclosed on the side toward the center of the macrospore. The 
unenclosed nucleus divides, and the daughter nucleus nearest the periphery 
of the macrospore becomes enclosed by a wall. The free nucleus continues 
to divide in the same manner, one of the resulting nuclei constantly passing 
outward and toward the center of the macrospore, until all are enclosed. 
The enclosed nuclei near the apex of the spore continue dividing, and 
become separated by new walls. New cells are formed more rapidly along 
the periphery of the macrospore, but are more tardily extended toward the 
center. Cell formation is not usually completed in the basal and central 
parts of the macrospore when archegonia are fully formed at the apex. 
The process in Selaginella is so similar to that in Isoetes that the same 
figures might easily serve to illustrate both. The nuclei divide and become 
enclosed in the same way, the prothallia are in about the same stage of 
development when the archegonia appear, and even the comparative size of 
cells in homologous portions of the prothallia is the same. In Selaginella 
no diaphragm appears separating the prothallium into vegetative and repro- 
ductive parts. In Isoetes the archegonia do not become green 
It becomes evident that the processes here observed are very similar to 
endosperm formation in the spermatophytes. Much more evidence upon 
” Lbid. 127-130. 9° Kew Bulletin 119: 207-215. 1899. 
*Pittonia 3:99-106. 1896. — 
Die Entwickelung des weiblichen Vorkeimes bei den heterosporen Lycopodi- 
aceen. Bot. Zeit. 9 : 159-168. 1896 
