720 Beer . — Studies in Spore Development . //. 
have found in Vida Faba that the somatic chromosomes form a con- 
tinuous spireme which subsequently segments into the constituent chromo- 
somes. Both Allium and Galtonia , upon the other hand, resemble Crepis 
virens in possessing no continuous spireme. This is clearly shown in the 
writings of Gregoire ( 11 ) and Miss Digby ( 4 ). 
Although not always to be seen, a certain amount of polarization of the 
developing spireme is sometimes noticeable in Crepis. An exceptionally 
marked case of such polarization was observed in the premeiotic division of 
one of the archesporial cells of the anther of this plant (Fig. 67). 
The chromosomes next proceed to shorten and thicken ; a spindle 
develops in the usual way, and the chromosomes are drawn upon the equator 
of this structure. At this stage the form and number of the chromosomes 
are very clearly to be seen. In a large number of cases there appears to be, 
as Rosenberg has shown, a constancy in the relative sizes of these bodies. 
In Fig. 68 it is seen that there are present two large chromosomes, two small 
ones, and two of an intermediate size. Each chromosome is distinctly 
divided longitudinally. My figure corresponds almost exactly with Rosen- 
berg’s Fig. 4, Plate I ( 20 ). It must be pointed out, however, that this 
definite distinction in the sizes of the chromosomes is not always so easy to 
see. In Fig. 69, which shows the metaphase of another nucleus of Crepis 
virens , these relative sizes of the chromosomes are not nearly so clearly 
expressed. In such cases the action of the fixative may most likely have 
had some effect upon the form of the chromosomes and the direction from 
which they are viewed (whether slightly obliquely or not) may also influence 
the result. On the whole I am inclined to agree with Rosenberg that the 
six chromosomes of this plant occur constantly in the relative sizes which 
he has described. The two halves of each chromosome are drawn apart 
and distributed to the two poles. At this time (late anaphase) some of the 
daughter chromosomes have the form of bent rods with one long limb 
bearing a short hook at the end (Fig. 70 a). At the poles the chromosomes 
shorten considerably and become very closely pressed together (Fig. job). 
They next again separate slightly from one another and become alveolized. 
No doubt the same causes which are at work in separating the meiotic 
chromosomes during the telophase are also active here. 
A nuclear wall is then formed round the chromosomes and the karyo- 
lymph which has begun to accumulate between them (Fig. 71). In by far 
the greater number of cases which have been observed the alveolization of 
the chromosomes takes place in such a way as to divide these bodies into 
two longitudinal halves (Fig. 71). Moreover, during the loosening of the 
ball of daughter chromosomes their viscid substance has remained adherent 
at certain spots, and it becomes drawn out into connecting filaments as the 
separation of the chromosomes proceeds. In a much smaller proportion of 
cases the central vacuolization of the chromosomes is not so apparent, and 
