394 DAVID H. TENNENT 
work which has been done up to this time has gone no further, 
with respect to the chromosomes, than the determination of the 
presence ‘of the haploid number and that in general the chromo- 
somes were rod-like in form. 
Within the past five years, partly from the knowledge that in 
Echinoderms chromosomes of different form are associated with 
different species and partly from the knowledge of chromosomes 
showing peculiarity of form in other phyla, the necessity of a fur- 
ther insight into the conditions existing in chemically fertilized 
eggs has arisen. 
This new study of the chromosomes in artificially partheno- 
genetic eggs has brought out the fact that all of the eggs are alike 
in that in each anaphase plate there are two V-shaped chromo- 
somes. 
It must be mentioned again that in many instances it is ex- 
tremely difficult to determine the V-shaped elements in the spin- 
dle. The arms of the V are frequently in contact with each other, 
giving the chromosome the appearance of a very thick rod. In 
some cases it is possible to ascertain that the rod is actually double; 
in others it becomes a matter of deduction. The conclusions 
reached are based on the study of a large number of spindles and 
where it has been necessary to make an interpretation of the 
nature described, it has been made in accordance with the evi- 
dence given by the clearer spindles and not with a preconceived 
idea of what the conditions should be. 
It is noteworthy that the best chances for an exact determina- 
tion of this form of the chromosomes is afforded by eggs in which 
the number of asters is above the normal. This is due to the 
fact that in such eggs the chromosomes are widely scattered. 
In fig. 1 A and B a multipolar spindle with apparently six asters 
is shown. There are eight V’s (four pairs) shown in this egg, 
three passing to pole A, three to pole B, one to pole E and one to 
pole F. The most probable explanation of the condition shown 
here hes in the assumption of the doubling in number of the chro- 
mosomes by a monaster division, followed by the multipolar 
divisions shown in the illustration. Such a method of behavior 
may be seen in many of the living eggs during the early develop- 
