‘ 
284 BOTANICAL GAZETTE [ocrosEr 
_ 7. Inthe mature plasmodium spore formation is preceded by repeated \ 
nuclear division of the typical mitotic sort. 
8. In the first period of its development the parasite does not kill the 
host cell, but merely causes it to hypertrophy.— CHARLES J, CHAMBERLAIN. 
HERBERT J. WEBBER, who has long been investigating the subject of 
plant-breeding for the Division of Vegetable Physiology and Pathology, U. 5. 
Department of Agriculture, has published his results upon xenia in maize, 
which means the immediate effect of pollen upon structures outside of the 
embryo. His experiments are by no means complete, but they have already 
yielded suggestive results, and the author is justified in their publication by the 
fact that the subject has been brought under discussion by the discovery 
the explanation of xenia. Mr. Webber had already reached the same 
conclusion independently, and was collecting a large amount of experimental 
data to substantiate his more leisurely developing paper. 
It seems that the name “‘xenia” was applied to this phenomenon by Focke.* 
While it is claimed to be a somewhat common phenomenon in many plants 
there are very few cases on record that are not open to doubt, and in 
no plant is its occurrence so well substantiated as in maize. The experimen's 
of Mr. Webber have been conducted since 1898, in Washington and at the 
‘Nebraska Agricultural Experiment Station. The greatest care was used to 
obtain pure races and to prevent the access of foreign pollen. Full details 
are given of about thirty experiments which yielded pertinent results, and the 
paper closes with their discussion. : 
The author abundantly confirmed Kérnicke’s statement that xe 
shown only in the endosperm. Color in the endosperm is frequently ap 
mitted by the pollinating parent, but color in the pericarp 1s ame 
chemical composition of the endosperm is also greatly affected by ue pollin- | 
ating parent, sweet corn crossed with dent or flint races producing re 
grains with starchy endosperm, and vice versa. All of the experiments ae 
the theory that xenia in maize is caused by the fertilization of the gene ’ 
nucleus by one of the male cells. All of the grains showing xenla — 
be true hybrids. In the case of spotted grains the author proposes an ap ; 
ing hypothesis by way of explanation. He suggests that the male nu 
may fail to fuse with the polar nuclei, and in such a case may 
a spindle and divide separately. In this event.two races of ie two 
be formed, and when the parietal placing and tissue formation beg age 4 
races might become intermixed. A second hypothesis éxplaining pats me 
homenon suggests that the male cell fuses with but one of the i ee 
nia is 
*5 Xenia, or the immediate effect of pollen, in maize, Bulletin 27, — 
(one colored). Issued September 12, 1900.‘ : 
**Die Pflanzen-Mischlinge 511. 1881, 
