1905] CURRENT LITERATURE : 377 
“thick spirem.” During synapsis the dual nature of the filaments is evident. 
It is due to a longitudinal approximation of two filaments and leads to the forma- 
tion of the thick spirem. The so-called longitudinal division is merely the 
reappearance of the line of approximation. Consequently the reduction in the 
number of chromosomes seen in the prophase of the heterotypic division is only 
an apparent reduction, due to the approximation of two somatic chromosomes, 
which in the mature chromosomes play the réle of daughter chromosomes. The 
reduction is really accomplished by the first mitosis, which separates these daughter 
chromosomes 
The third paper?! in the series deals with microsporogenesis in Convallaria 
majalis. The results confirm the conclusions already drawn from the author’s 
study of Allium fistulosum and Lilium speciosum. The two daughter chromo- 
somes which constitute the mature heterotypic chromosome represent two longi- 
tudinal parts of one segment of the thick spirem. This thick spirem is formed 
by the longitudinal approximation of slender oe ey Seite by ais 
This approximation takes place during th 
takes place in the strepsinema stage, resuietere fe in an apparent sper Si division. 
The heterotypic division is a reduction division, which distributes to the two 
poles complete somatic chromosomes.—C. J. CHAMBERLAIN 
THE RESEARCHES of SCHWARZ, ELFVING, VoCHTING, RAcrBoRSKI, and others 
on the influence of gravitation upon the rate of growth of erect and inverted organs 
(vertical) is not affected by gravitation, such organs when inverted manifest a 
checking of the rate of growth in length. Improvement upon ELFvinc’s tech- 
nique was secured by using artificial light of constant intensity instead of sun- 
light for keeping the organs parallel with gravitation; also by substituting a non- 
shrivelling substratum for enue crumbs for the growing of fungi. For such 
organs as could not be t 1 in a vertical position by = ee of light, recourse 
was taken to the use of pulleys and weights. The expe terial employed 
includes both positively and negatively geotropic organs as found in members of 
various genera of fungi, of apie s, and of dicotyledons, as well as the 
branches of weeping trees. While nodes of grasses constitute an viet HO the 
uniformity of behavior revealed by numerous other forms is so great to permit 
a formulation of this general statement, namely, parallelotropic ses as 2 
consequence of inversion suffer a reduction in the rate of growth in length. In the 
case of the sporangiophores of Phycomyces prolonged inversion is followed by 
-_-— 
« BeRGHS, JULES, La formation des chromosomes hétérotypiques dans la sporo- 
wha végétale. III. La microsporogénése de Convallaria majalis. La Cellule 
53: pl. 4. 
22 HerInc, GeorG, Untersuchungen iiber das Wachsthum inversgesteller Pflanz- 
€norgane. Jahrb. Wiss. Bot. 40:499-562. 1904. 
