246 BOTANICAL GAZETTE [SEPTEMBER 
and that the incapacity for plasmolysis is due to a hardening of the protoplasm. 
The main evidence for the hardening of the protoplasm is the failure of chloro- 
plasts to be displaced by a centrifugal force of about 1000 gravities, which 
ordinarily displaces them readily. This process of hardening is reversed (physico- 
chemically and physiologically) by transferring the cells to aluminium-free 
solutions. The slow rate of reversing leads the author to postulate the tying up 
of the aluminium in an indiffusible form. It is only in moderate concentrations 
that aluminium salts produce the effect; in higher concentrations the protoplasm 
does not harden. Anthocyanin cells cannot be thus hardened, probably due to 
high sugar content. The author relates this to the fact that non-electrolytes 
hinder the precipitation of proteins by ions. He also thinks that aluminium 
salts are specific only in that their low toxicity enables them to bring about such 
a fundamental physical change in the protoplasm without killing it. While most 
salts produce such a change, it is not physiologically reversible WILLIAM 
OCKER. 
Individuality of the chromosome.—A four-years’ study of the vegetative 
and reproductive nuclei of Carex aquatilis has brought Strout“ to the conclusion 
that the chromosome is an individual organ, maintaining its identity through 
successive cell generations. He finds that even in restin g nuclei the chromosomes 
are visible as definite bodies which can be counted, and that these chromosomes 
can be traced through all the stages of vegetative and reduction divisions, except 

Seedling anatomy.—Hirt and DeFratne‘ have worked long enough upon 
anatomy to have come to some very interesting conclusions. Citing 
— facts that have been used in phylogenetic conclusions, they state that 
they “see no necessity for preservin seedling anatomy from the fate already 
meted out to other structural features which were at one time considered as 
Santon SORE 
“Stout, A. B., The individu 
; ality of the chromosomes and their serial arrange 
ment in Carex aquatilis, 
Archiv. Zellforschung Q:114-140. pls. II, 12. 1912. 
47 
struct me iv G., and DeFraing, E., A consideration of the facts relating to the 
ure of seedlings. Ann. Botany 27: 257-272. 1913. 
