1900] CURRENT LITERATURE 219 
grass leaves. The former may be of some service ; such schemes as the 
latter embodies are useful enough for the note book, but only cumber litera- 
ture—C, R. B 
OUR KNOWLEDGE of the life history of the Gnetacez has been considera- 
bly increased by Lotsy’s 3 recent work on the life history of Gnetum. The 
difficulty in procuring material is responsible for the fact that comparatively 
few observations have been made. Of the three genera which compose the 
group, Welwitschia is found only in Damaraland, Ephedra is a desert plant, 
and the remaining genus, Gnetum, is found only in the tropics. Moreover, 
as in case of most gymnosperms, the collecting must extend over a considera- 
ble period in order to insure anything like a complete series of stages. 
Dr. Lotsy’s stay at the Buitenzorg botanical gardens in Java enabled him 
to secure a very complete series of stages in the development of Gnetum 
gnemon, from the earliest appearance of the flowers up to the formation of the 
embryo. 
The inflorescences of Gnetum gnemon are spikes which come from the 
axils of opposite bracts. On each spike is a series of cups which owe their 
origin to a concrescence of bracts. At the base of each cup is a ring of 
tissue, upon the upper part of which may be seen a number of small, cone- 
shaped, greenish bodies ; these are the female flowers. The mature female 
flower has three envelopes, which are formed in acropetal succession. The 
rudimentary female flowers found on the staminate spikes have only two 
envelopes. 
The author regards the outer envelopes as whorls of bracts, which, for 
convenience, may be called the internal and external perianths. The inner 
envelope, which is longer and projects above the other two, he regards as an 
integument. 
At the period of pollination a drop of fluid appears at the top of the integu- 
ment, and consequenily the term integumental stigma is applied. Pollination 
1s probably effected by the wind, though it may be that insects have some 
part in it. 
degeneration of cells in that region. Before reaching the embryo-sac the 
pollen tube contains a tube nucleus and two generative nuclei. 
of spermatogenesis are reserved for a future paper. Each nucellus contains 
Several macrospores which originate as in well-known gymnosperms. The 
in Pinus or 
other familiar forms, there being first a series of nuclear divisions, so that a 
large number of nuclei lie free in the protoplasmic lining of the embryo-sac. 
The history from this stage differs from that of other gymnosperms. A con: 
Striction appears somewhat below the middle of the sac, reducing the lumen 
¥, J.: Contributions to the life history of the genus Gnetum. Ann. du 
3 Lots 
Jardin Bot. de Buitenzorg. II. 1: 46-114. p/. 2-77. 1899. 
