~ Ernst, A. ('02), Chromosomenreduction, Entwickelung des Embryosackes 
1904] BRIEFER ARTICLES 469 
of intimate contact, a mutual interaction, or even an interchange of 
hereditary units occurs. The pairing of the parental chromosomes 
postulated by De Vries may be conceived to be effected by the method 
described by Farmer and Moore (’03), who hold that each apparently 
double chromosome is formed by a transverse bending of one of the 
original segments of the spirem. Ifit be maintained that one of the seg- 
ments which thus folds upon itself represents a paternal and a maternal 
chromosome attached end to end, it would seem to follow that in the 
spirem of a somatic mitosis the parental elements are arranged in 
regular alternation. If the views expressed in the present paper be 
correct, it is more probable that the chromosomes derived from the 
male parent are attached end to end to form a thread, and that those 
from the female parent are arranged into a similar thread ; and that ina 
somatic mitosis these two threads in turn unite by their ends to forma 
continuous spirem 
The peculiarities of the heterotypic division described by Rosen- 
berg (’04) in a hybrid Drosera, in which ten single and ten double 
chromosomes appear, may be accounted for by supposing a fusion of 
the two parental portions of the spirem in the early prophases. ‘The 
portion derived from one parent, containing only ten segments, would 
extend only half the length of the other portion, containing twenty 
segments; the thread on segmenting would therefore give rise to ten 
segments of double thickness and ten of single thickness, the latter 
perhaps incapable, in this division at least, of longitudinal splitting. 
—CHARLES E. ALLEN, University of Wisconsin, Madison, Wis. 
OTE.— Since the above was written, there has appeared a further 
account by Rosenberg (’04 a) of the post-synaptic processes in Drosera, He 
is desl ate that there is a fusion of the chromosomes side by oie during 
e spirem stage. Strasburger (’04), on the other hand, has described in 
ee lictrum a quite st method of conjugation of the paternal and 
maternal chromatin in entire independence of the linin. -A. and K. E. 
Schreiner (’04) have found a fusion and subsequent splitting of the spirem, 
substantially identical with the processes I have described, in the spermato- 
‘genesis of Myxine 
and Spinax; and similar results had been previously 
announced by von Winiwarter (’00) and Schoenfeld ('o1) with respect to 
mammalian oogenesis and spermatogenesis. 
LIFERATURE CITED. 
und Befruchtung bei Paris guadrifolia L.und Trillium grandiflorum 
Salisb. Flora 91:1 
