—_ 
LOAN Syd NIP io et tein Nadie noe ate) ght Seen ae a er Soh oe ll eal aD 4 
1897 | CURRENT LITERATURE 22% 
Boronieae, which display a wide range of nearly related forms of limited dis- 
tribution ; (2) groups, as Xanthoxyleae-Evodiinae in eastern Australia, and 
Xanthoxyleae-Decatropidinae in Mexico and West Indies, which show a con- 
siderable number of widely separated forms or genera confined to limited 
areas ; (3) groups and genera possessing more or less numerous forms in 
widely separated localities ; (4) single groups and genera of few forms which 
occur in widely separated regions ; (5) certain isolated genera, as Spathelia, 
Chloroxylon, and Dictyoloma, whose derivation the author believes to have 
been from a stock distinct from that of the more widely distributed groups of 
Rutaceae. By means of color upon map outlines, three handsome plates, 
which accompany the text, graphically represent the distribution of par- 
ticular genera, and by elucidating the text add greatly to the comfort of the 
reader.—J. G. C. 
NOTES FOR STUDENTS. 
THE ALMOST simultaneous announcement of the discovery of spermato- 
zoids in Ginkgo biloba and Cycas revoluta™ is one of the most startling 
botanical announcements of recent years. The work of Ikeno upon Cycas 
revoluta, begun three years ago, attracted attention from his announcement 
of a distinct ventral canal cell," the existence of which was in doubt. These 
various announcements, however, are very brief and are but preliminary to 
the full illustrated papers which will be awaited with great interest. 
In the case of Ginkgo biloba Hirase has observed the following facts: 
The pollen grain consists of two prothallial cells and the tube cell, the latter 
developing a much branched tube, the branches of which spread out over the 
cna of = nt reenapas nell gc LR: of es two prothallial cells 
. The generative cell 
then divides and the two daughter cells fox motile aR Ae ane instead of 
the customary non-motile male cells. e ozoids are egg shaped, 
49 X 82u, and have a central nucleus completely surrounded by cytoplasm. 
The head consists of a three-coiled spiral with numerous cilia, and a pointed 
tailwas also observed. Within the nucellus above the archegonia there is 
an abundant liquid, probably secreted by the archegonia, in which the 
spermatozoids were observed to swim about with a rotating motion. 
In Cycas eek tious obtained almost identical results. The sperma-— 
tozoids are a little larger than those of Ginkgo and the head isa spiral with 
four turns bearing numerous cilia. The production in each pollen tube of 
2S. Hirase (Tokyo) in Botanical Agrees, § Oct. 1896, and in Bot. Central. Jan. 
14, pe 
S. Ikeno (Tokyo) in Botanical Magasine ox ee Bot. Central. cscs 
18 
Bot. Central. 33: 193. 00. 
