May, 1906.] 
.4 Reducing Division in Ascaris. 
521 
of the chromosomes (already longitudinally divided) two by two 
forming combinations of four members. 
From the resting nucleus a continuous spirem is formed in 
the usual manner (figs. 1-3). In Ascaris the spriem is very 
closely wrapped so that it is a very difficult object to resolve and 
cannot be untangled and traced out with confidence. This 
however is a matter of no great moment in the present discussion 
since the occurrence of such a spirem is well known. In some 
cases (fig. 1-2) even before the spirem is formed the chromatin 
is distinctly separable into two masses. Such a separation may 
(fig. 5) or may not (fig. 3-4) be evident in the spirem. 
Before the contraction of the spirem has proceeded far the 
granules rvhich are strung along the linin thread become doubled 
(fig. 4). At first very difficult to observe, the distance between 
the doubled granules becomes greater and greater till the linin 
thread splits and two parallel sprimes are formed (fig. 5). It 
has been maintained recently by Berghs (1) that in the flowering 
plants these doubled granules arise not by' a longitudinal splitting 
of the spirem as has hitherto been supposed but by the conjuga- 
tion of the granules from two separate strands of linin. Whether 
the doubled spirem in Ascaris arises in such a manner or by' a 
split does not seem to me susceptible of complete demonstration. 
I see, however, no reason for abandoning the older interpreta- 
tion ; while there are several indications that point toward a 
splitting rather than to a conjugation. (1) The spirem at the 
earliest stage where the doubling appears (i. e. earliest as judged 
by’ the relative state of contraction of the spirem) is of approxi- 
mately’ the same length (fig. 4) as the single spirem preceding 
(fig. 3), while if a conjugation took place it would be of only half 
the length. (2) At the earliest stage where the doubling is visi- 
ble, judged by’ the same criterion, the granules lie exceedingly 
close together and from this stage they recede up to a stage rep- 
resented by’ fig. 5. while if they’ were the result of conjugation 
we should expect the opposite. 
Very frequently’ in split spirems (fig. 5) the linin at one end is 
bent into the form of a square with a prominent granule at each 
comer. The granules are so much more prominent than the 
linin thread upon which they are strung that one might easily 
suppose that he was looking at the end of a set of granules doubly 
split instead of at the side of a continuous spirem. In the cases 
observed however there was no great difficulty in tracing the 
course of the spirem and showing that such was only a superficial 
appearance. The spirem in this stage often foreshadows quite 
plainly the tetrads destined to be formed from it. In its contrac- 
tion it is often thrown into two loops each arm of which is double 
giving therefore two groups of four strands each. 
