1908] CURRENT LITERATURE 233 
found an objection, especially where a considerable increase of the ovocyte is 
not followed directly by nuclear division. For the sake of harmonizing the 
theory with the phenomena, he suggested that synapsis is really an abortive 
division. This theory of synapsis naturally tends to interpret synapsis not as a 
stage preparing for the heterotypic chromosomes, but only as an abortive form of 
nuclear division. The work of Poporr on ovogenesis of Paludina is the material 
on which the theory is based. Poporr apparently considers the bivalent chromo- 
somes after synapsis and before the growth period in ovogenesis of Paludina as 
tetrads. These chromosomes completely disorganize in the diplonema stage, 
and the heterotypic chromosomes which appear after the growth period are a new 
formation, without any connection with the chromosomes that emerged from 
synapsis. Moreover, WasstLerrr considers that in spermatogenesis of Blatta 
there occurs a pulverization of chromosomes during synapsis, and he believes that 
it is a trace of abortive nuclear division. 
G TRE remarks, under the headings spermatogenesis, sporogenesis, and 
Svogenesis, that such an interpretation cannot be in harmony with the vast major- 
ity of cases of synapsis, which are believed to be an important stage in the prepa- 
ration of heterotypic chromosomes. In conclusion, he emphasizes synapsis as a 
fundamental stage, which constitutes a primary state of heterotypic prophase 
and not as an abortive kinesis.—Suicéo YAMANOUCHI. 
Soil fertility-—The Bureau of Soils is doing an excellent work in seeking the 
explanation of the differences in productiveness of soils along the lines of a rational 
Physiology - In spite of various attacks upon the principles which they are devel- 
oping, the work commends itself to the unprejudiced as consonant with the modern 
Phases of physics and physiology. Two recent bulletins contain valuable reports 
of research. Cameron and GALLAGHER have shown‘ that when water has been 
added to a given soil in such proportion that it is in its most favorable condition 
for working and for plant development (as determined by expert gardeners), this 
1s also the condition when to a pointed inst t it is physically most penetrable 
This “optimum” water content varies with different soils from 4 per cent. (sandy) 
0 120 per cent, (muck). The apparent specific gravity or volume, the rate of 
‘vaporation, and some other physical features are also definitely related to the 
moisture content, changing in a marked way as the optimum water content es 
- It is also shown that the optimum moisture does not vary with the 
Plant, but what is best for one plant is best for another in a given soil. Probably 
the Penetrability of the soil is the important factor, since roots are thus able to 
Teach their maximum development, and so to offer the largest possible surface me 
the admission of water. 
__Another bulletin, by GarDNeER,’ reports a vast number of aa on 
.. “CAMERON, F. K., and , F. E., Moisture content and physical con- 
dition of soils. “U. g., Dept. a of Soils, Bull. 50. pp. 70 figs. 33- Jan- 
FY 31, 1908, 
*Garpner, F. D., Fertility of soils as affected by manures. Idem, Bull. 48. 
PP 59. figs. 5+ March 2x, 1908. 
