1914] CURRENT LITERATURE 541 
cell has several nuclei, and nuclear division continues after the mother cell 
has become recognizable, but the number of nuclei seldom exceeds a dozen. 
In the vegetative mitoses the chromosomes are organized directly from the 
reticulum, but in the tetraspore mother cell the formation of chromosomes is 
preceded by a typical spirem stage. After the number of nuclei reaches 
about a dozen, some begin to disorganize, but several may develop spirems 
and continue up to a typical metaphase of the heterotypic mitosis; then one 
nucleus continues and all the rest disorganize. The details of the division of 
the successful nucleus and the organization of tetraspores agrees fully with the 
account given by YAMANOUCHI for Polysiphonia.—CHARLES J. CHAMBERLAIN. 
Distribution and development of an Ohio flora.—A region in southern 
Ohio designated as “‘Sugar Grove”’ and situated at the end of a long lobe of 
Merriam’s Alleghenian floral area, is regarded by Griccs'’ as remarkable on 
account of its being the meeting place of many very diverse floras. He has 
mapped six such groups, consisting of (1) Alleghenian plants, 39 species 
(2) Appalachian plants (northern), 14 species; (3) Appalachian hits ee 
ern), 12 ' Species; 4) Carolinian plants, 12 species; (5) Mississippian plants, 
i nds $ 
121 plants are scanty, as the author admits, but that many of these species are 
near the limit of their distribution seems quite evident. This has led to an 
appear the responses that it would seem difficult to draw any general conclu- 
sions, although the author decides that the limits of species reaching the edges 
of their ranges near Sugar Grove are not fixed, but are changing, and that 
plants of boreal affinity are apparently being displaced by others from the west 
and south, a continuation of the floristic movements following the glacial 
period. Tsuga canadensis is cited as an example of such movements, and 
Griccs asserts that it is now found in southern Ohio only because it has not 
been completely displaced by the post-glacial flora, and occupies its habitats 
simply because within them the invading hardwood forest has not had so 
good an opportunity to gain a foothold as elsewhere. This explanation seems 
plausible, but the reviewer cannot regard the case as proved.—GeEo. D. FULLER. 
Prothallium of Equisetum.—KasuyapP* has investigated the prothallium 
of Equisetum debile as it grows in abundance in the vicinity of Lahore, India. 
3 Griccs, R. F., Observations on the geographical composition of the Sugar 
Grove flora. Bull. Torr. Bot. Club 40:487-499. 1913. 
4 Griccs, R. F., Observations on the behavior of some species at the edges of 
their ranges. Bull. Torr. Bot. Club 41:25-49. 1914. 
s Kasuyap, Sutv R., The structure and development of the prothallium of 
Equisetum debile Roxb. Ann. Botany 28:163-181. figs. 45. 1914. 
