156 CANNON: STUDIES IN PLANT. HyBRIDS 
author treats the matter somewhat more fully and cites the work 
of Rikert and Hacker on Cyc/ops, and Herla and Zoja on Ascar‘s. 
Recently Hacker * has confirmed and extended his earlier con- 
clusions, and in a recent paper Moenkhaus states that he has 
found that the paternal and the maternal chromatin may remain 
separate and distinct during several cell generations in hybrid 
fishes. 
It has already been stated that the conjugation of the chro- 
mosomes occurs in pure races at some stage before the matura- 
tion divisions, and that by the separation of the chromosomes, 
provided they are lineally descended from parental chromosomes, 
the spores may be of pure descent. Now when in certain hybrids 
the conjugation fails to take place a mother-cell with a two-spindle 
nucleus may be formed as Guyer has stated, + and as he has 
shown in the fertile hybrids studied by him. Metcalf also found 
in hybrid Gladiolus, as I have mentioned in summarizing his work, 
chromosomes in two masses as on double spindles in the pollen- 
mother-cells and, finally, I have observed a few mother-cells in 
the hybrid cotton which may apparently had double spindles. In 
the cotton, however, this condition was the exception, as will be 
spoken of below. 
Phenomena which are probably associated with the indepen- 
dence of the germ-nuclei have long been observed in hybrids. 
These comprise the greater influence of the one than the other 
parent, or, at the other extreme, the equal influence of both 
parents in the hybrid. Between these extremes are many inter- 
mediates some of which have already been mentioned (page 142). 
And it seems possible that in some hybrids the germ-nuclei may 
equally and independently mold the character of the cells, and 
not combine to effect this as in strictly intermediate hybrids. Far- 
mer,} for example, gives an account of a hybrid Oxa/zs in some 
epidermal cells of which “richomes typical of both parents may be 
found in a single cell. Other cases illustrating this point might 
also be cited. It will thus be seen that a close study of the struc- 
* Hacker, Ueber die Autonomie der vaterlichen und miitterlichen Kernsubstanz 
vom Ei bis zu den Fortpflanzungszellen. Anat, Anzeiger, 20: 440-452. 1902, 
f{ Guyer. Science. II. 15 : 530. 1902. 
{ Farmer. Ann. Bot. 11; 542. 1897. 
