224 
Katharine Foot and E. C. Strobell 
could demonstrate its second division made us very skeptical of the signifi- 
cance attributed to its frequent non-division, and created a doubt as to 
whether the cases in which it failed to divide were normal. We were 
careful to confine our demonstration to the fact that the accessorv chromo- 
some can divide in the second spindle, and we claimed, and still claim 
that not until the fundamental significance attached to the non-division 
of tliis chromosoine can be established, can its demonstrated division in 
Anasa tristis be justly set aside as abnormal. 
Front the point of view of variability Edward's results in Ascaris 
megalocephala are of interest. Out of a lot of forty-five individuals he 
finds two which show an accessory chromosome in the maturation divi- 
sions and further, the method of division of the accessory chromosome 
is variable. “Studying a great number of males, I have fonnd in one lot 
of forty-five front one horse two individnals, wornts A and B in which 
an idiochromosome can be followed throughout the whole maturation 
period, and another wornt C, front which unfortunately the division 
section was lost, bnt which shows the idiochromosome in the primary 
spermatocytes” p. 424. 
In worm A the accessory chromosome divides in the first spindle, 
whereas, he adds, “In worm B most often in this first maturation division, 
the idiochromosome passes undivided to one of the secondary spermato- 
cytes (pl. XXI, fig. 3). Although it is sometimes divided 1 ) and 
distributed just as described for worm A” p. 425. 
In worm A the accessory falls to divide in the second spindle, whereas, 
“in worm B the two halves of the idiochromosome which at the end of 
the first maturation division lodged undivided in one of the two secondary 
spermatocytes, are distributed in the second division to the daughter 
spermatids (pl. XXI, fig. 21)” p. 425. 
When such variations occur in the same individual it has been sug- 
gested as an explanation that a Variation in one spindle may be corrected 
in the other, but this cannot hold for Anasa tristis. It caiinot be said 
that in those cases in which the accessory divides in the second spindle, 
it must have failed to divide in the first spindle, for the method of division 
and the form of the chromosomes are quite different for the two spindles — 
in the first spindle it divides longitudinally and in the second transversely. 
If the significance holds which has been attributed to the failure of this 
chromosome to divide in one of the two maturation divisions, then those 
cases in which it divides twice in Anasa must be set aside as pathological. 
1 ) The italics are ours. 
