1905] CURRENT LITERATURE 429 
remains unable to account. Attempts to correlate with external conditions the 
storage organs is possible, while PuRrEWwITsCH believed complete depletion pos- 
sible. WACHTER believes from his results that the density of the external medium 
is not a factor in depletion, for he found that even with exosmosis inhibited the 
density of the cell sap was greater than that of the external fluid. The author 
remains uncommitted as to the fluctuating permeability of the plasma, and insists 
that further investigation is necessary to answer this question—Raymonp H 
OND 
THE X-GENERATION and the 2x- eave ag is the title of an interesting 
philosophical paper by Lotsy.?. The nuclei of the x-generation contains only 
one-half the number of chromosomes as do the ie of the 2x-generation. Only 
asexually reproducing organisms have the x-number of chromosom The 
which generation should be called the x-generation? If the fern clas is the 
x-generation, the prothallium is a 4$x-generation; if the prothallium is the x-gener- 
ation, the fern plant is a 2x-generation. The behavior of the chromatin during 
fertilization and during the reduction of chromosomes shows that the x-generation 
is the primitive generation, and that the 2x-generation is later, and that its double 
number of chromosomes is due to fertilization. Thus the ancient question of 
the philosophers, which came first, the hen or the egg, can be answered by merely 
counting the chromosomes. The 2x-generation cannot exist indefinitely, but 
sooner or later must form reproductive cells in which the primitive number o 
chromosomes is restored. This reversion to the x-generation consists in the 
Separation of the paternal and maternal chromosomes. The process is preceded 
by the pairing of these chromosomes, which have remained separated throughout 
the vegetative life of the organism. Numerical reduction of chromosomes is the 
expression of this pairing. Lorsy does not hesitate to apply the theory to animals, 
the body representing the 2x-generation, while the x-generation is reduced to the 
sexual cells.—C. J. CHAMBERLAIN. 
THomson® has been investigating the megaspore membrane or coat of gym- 
nosperms, naturally applying the term to the investing coat of the prothallium 
as well as to the coat of the uninucleate spore. This coat is present in all gym- 
hosperms except the Taxeae, among which it is entirely eliminated or nearly so. 
It consists of two layers, the outer one being suberized, while the inner one is 
the megaspore coat resembles in structure and composition the microspore coat. 
The only exception to this general character of the megaspore coat is found among 
7 Lorsy, J. P., Die x-Generation und die 2x-Generation, eine Arbeitshypothese ” 
Biol. Centralbl. 25:97-117. 4 diagrams. 1905. 
8 THomson, R. B., The megaspore-membrane of the gymnosperms. Univ. of 
Toronto Biol. Series, No. 4, pp- 64. pls. 5. 1905 
