232 BOTANICAL GAZETTE [MARCH 
DouGLas H. CAMPBELL has published a second paper upon the Ara- 
cea: dealing chiefly with Ag/aonema commutatum and Sfathicarpa sagittae- 
archesporial cell or may possibly originate independently from hypodermal 
’ cells. The most interesting feature, however, is the variation in the number of 
nuclei in the embryo-sac, this ranging from four to twelve and with slight 
indication of polarity. Multiple nuclear-fusions are of common occurrence, 
and it is often impossible to be certain which of the structures represent the 
egg-apparatus and which the antipodal cells. The embryo of this species 
also conforms to what seems to be an aroid type, namely a large mass of 
cells with little differentiation of external parts and with tissues almost com- 
pletely homogeneous. 
In Spathicarpa the embryo-sac is of the ordinary angiospermous type, 
but after fertilization the antipodals become greatly enlarged and one of them 
may divide. The embryo remains small and the external organs are evident, 
but the tissues are only slightly developed. 
In both species the development of endosperm proceeds gradually Sie 
the base of the embryo-sac until it is completely filled.— J. M. C 
_ DEANE B. SWINGLE®% in his study of the formation of spores in Rhizo- 
pus and Phycomyces has summarized the essential features of the process as 
follows : (1) streaming of the cytoplasm, nuclei, and vacuoles up the spo- 
rangiophore and out toward the periphery, forming a dense layer next the 
sporangium wall and a less dense region in the interior, both containing 
nuclei; (2) formation of a layer of comparatively large, round vacuoles in the 
denser plasm parallel to its inner surface; (3) extension of these vacuoles by 
flattening so that they fuse to form a curved cleft in the denser plasm; and, in 
the case of Rhizopus, the cutting upward of a circular surface furrow from 
the base of the sporangium to meet the cleft formed by these vacuoles, thus 
cleaving out the columella ; (4) division of the spore-plasm into spores; in 
Rhizopus, by furrows pushing progressively inward from the surface, and 
outward from the columella cleft, both systems branching, curving, and 
intersecting to form multinucleated bits of protoplasm, surrounded only fi 
plasma-membranes and separated by spaces filled with cell sap only; 
Phycomyces, by angles forming in certain vacuoles containing a pene 
substance and continuing outward into the spore-plasm as furrows, aided by 
other furrows from the columella cleft, and dividing the protoplasm into bits 
homologous with and similar to those in Rhizopus, and separated by furrows 
**CAMPBELL, DoucLas H. Studies on the Araceae. The embryo-sac and 
embryo of Aglaonema and Spathicarpa. Ann. Botany 17: 665-687. pls. 30-32. 
1903. 
25 SWINGLE, DEANE B., Formation of the spores in the sporangia of Rhizopus 
nigricans and of Phycomyces nitens. pp. 40. f/s. 6. Bulletin 37, Bureau of Plant 
Industry. 1903. 
