474 BOTANICAL GAZETTE [DECEMBER 
that in practically all cultivable lands no such influence exists. The soil 
water is at all times nearly saturated with the difficultly soluble minerals of 
which the soil is composed, and several hundred analyses of water from soils 
of every type and degree of fertility showed in almost every case that the 
materials essential for the plant are present in considerable excess of the 
amount required for the production of good crops. This result agrees well 
with the observations of students of physiographic ecology, that the chemical 
composition of the underlying rocks is of little significance in determining 
the development of vegetation, and it furnishes a sound basis for the explana- 
tion of this observed fact. It also emphasizes the importance of the study of 
soil physics, since it is in the physical properties of the soil that we must 
find the explanation of the important influences of soil upon vegetation. 
There are brief chapters upon the influence of climate, of texture of the soil, 
and rotation upon the yield of crops, and upon the réle of commercial fertili- 
zers. In an appendix is a concise description of the methods used for the 
quantitative determination of the various ingredients of soil waters. This 
will be greatly appreciated because of the simplicity of the a the 
ease of manipulation and the accuracy of the results.—G. H. SHULL. 
N THE RUST, Coleosporium sonchi-arvensis Lév.” during certain stages 
in the life history the cells contain two nuclei and at other stages but one 
nucleus. The uredospore and the cells of the mycelium to which it gives 
rise, contain two nuclei which divide by conjugate division, z. e., each nucleus 
contributes to each of the two daughter-cells. The teleutospore produced 
from this mycelium is the last binucleate cell of the series. The two nuclei 
of the teleutospore fuse, after which the teleutospore at once germinates into 
a four-celled promycelium, each cell of which contains but a single nucleus. 
Each of the four-cells of the promycelium produces a uninucleate sporidium. 
The first division of the nucleus of the sporidium is not followed by cell 
division, but starting with the sporidium there is developed a mycelium of 
binucleate cells. In short, from teleutospore to sporidium the cells are uni- 
nucleate, and from sporidum to teleutospore, binucleate. 
e two nuclei which fuse in the teleutospore have maintained a separate 
existence throughout almost the entire life cycle of the host, and there is 
some evidence that the chromosomes, in the division of the fusion nucleus, 
are collected into two groups representing, possibly, the chromosomes of the 
male and female nuclei. While there is no proper cell fusion, the union of 
nuclei more or less separated in origin is not out of harmony with our concep- 
tion of sexual reproduction in other groups of plants.—C. J. CHAMBERLAIN, 
RUHLAND has presented in full?" the results of his studies on several of 
° HOLDEN, R. J. and Harper, R. A., Nuclear divisions and nuclear fusion in 
Coleosporium sonchi-arvensis Lév. Trans. Wis. Acad. Sci. 14: 63-82. pls. 1-2. 1903+ 
2 RUHLAND, W. VON, Studien iiber die Befruchtung der Albugo Lepigoni und 
einige Peronosporeen. Jarhb. Wiss. Bot. 39:135-166. fis. 2. 1903. . 
