Beer. — Studies in Spore Development. II. 7 1 7 
depend upon the physiological condition of the cell at the time when it was 
fixed. One or two nucleoli have, meanwhile, made their appearance in 
these nuclei. 
In Tragopogon and Crepis (both species) the prophases of this division 
are not quite so simple. The material of the chromosomes of these plants, 
which was more or less distributed during the telophase of the heterotype 
division, now again becomes concentrated to reconstruct the chromosomes. 
In a number of cases this concentration is seen to take place from two sides, 
so that the young chromosomes are built up of two longitudinal halves with 
a clear space between them (Fig. 42). In these cases, therefore, the develop- 
ing chromosomes (and probably also the fully developed chromosomes 
as well) are longitudinally divided. This is strikingly different from what 
was seen to occur during the heterotype prophases and, as will be seen 
below, resembles the behaviour of the somatic chromosomes of these plants. 
It must be pointed out, however, that this concentration of the homotype 
chromosomes in two longitudinal halves is not always apparent. In several 
cases the chromosomes appear to concentrate as single, more or less homo- 
geneous bands (Fig. 43). This may, perhaps, in some instances be due to 
the aspect from which the chromosomes are viewed. Seen from a lateral 
or oblique direction the split would often be hidden by one of the sides, 
especially in those cases in which the chromosome material was still very 
diffuse. The chromosomes continue to become more concentrated, and they 
gradually assume a regular, smooth, and compact appearance. They become 
arranged in the form of a spireme (Figs. 44 and 46), which is probably discon- 
tinuous, although it is difficult to be quite certain of this point. In nuclei 
which are at a slightly more advanced stage the chromosomes are, however, 
very distinctly separated from one another (Fig. 45). 
At first they are long and slender, but they gradually contract into 
shorter and thicker bodies. The rod-shaped chromosomes which, after the 
disappearance of the nuclear membrane, are drawn upon the spindle in 
Tragopogon are seen in Fig. 47. The metaphase of the division is illus- 
trated in Fig. 48, which shows that the chromosomes of Crepis taraxacifolia 
are rather longer than those of Tragopogon. The early anaphase in Crepis 
virens is represented in Fig. 49. A later stage of the anaphase in Trago- 
pogon is shown in Fig. 50, from which it will be seen that the chromosomes 
of the plant become much drawn out and elongated during their passage to 
the poles of the spindle. In Fig. 51 the chromosomes of Tragopogon have 
reached the poles, and they then shorten somewhat again. A late anaphase 
in Crepis virens is shown in Fig. 52. There are some points of difference 
between the telophase of these plants (viz. Tragopogon and Crepis) and 
that of Matricaria. There is the same coherence of the chromosomes with 
one another, and the same separation of their bodies by the accumulation 
of a fluid between them, as is the case in Matricaria , but in Tragopogon and 
