597 
Gnomonia ery thro stoma , Pers. 
often observed that the chromatin network is not readily stainable at this 
stage (Fig. 29). This condition apparently persists for some time. The 
exact method of formation of the chromosomes of the first division could 
not be made out. No indications of loop formation have as yet been observed. 
Fig. 30 shows one of the few stages seen in the formation of the chromo¬ 
somes. It will be observed that four lumpy masses are being elaborated 
within the nuclear area. Spindle formation takes place in the same manner 
as that described by Harper ( 24 ) and Fraser ( 19 ) in other Ascomycetes. 
Distinct centrosomes of a discoid shape are present at the two extremities 
of the spindle (Fig. 33). While the chromosomes are in process of forma¬ 
tion the nucleolus becomes vacuolate (Fig. 30), and the nuclear membrane 
less clearly defined. Figs. 31-33 show the metaphase of the first division. 
In some cases the shape of the chromosomes of this division is strikingly 
like that of the heterotype chromosomes of pollen mother-cells (Fig. 34). 
They are short and thick, and in metaphase show a middle portion project¬ 
ing equatorially and two limbs directed along the spindle. Fig. 35 shows 
a late stage in the first division. This nuclear division is therefore to 
be interpreted as being one of reduction, though whether it is heterotypic 
or brachymeiotic one cannot say with certainty, since the exact details 
of chromosome-formation have not been ascertained. The shape of the 
chromosomes and the fact that the second division follows rapidly upon the 
first furnish analogies with meiosis rather than with brachymeiosis. 
In the reconstruction of the two daughter-nuclei a distinct nucleolus is 
formed (Fig. 36). Preparations showing the metaphase and anaphase of the 
second division have not yet been obtained, but the telophase is represented 
in Figs. 38, 39. 
The four nuclei thus formed rest for some time before undergoing the 
next division. The chromatin network of these nuclei is clearly marked. 
The nuclei often show a certain amount of polarity at this stage and a little 
later. Thus in Fig. 40 one nucleus shows the attachment of the chromatin 
net to one end of the nuclear membrane. Such a condition reminds one of 
the ascus nuclei of Phyllactinia , where Harper found very distinct polarity. 
A slight polarity has also been seen in the bi-nucleate stage of the ascus of 
Gnomonia. No clear contraction of the chromatin network, such as has been 
described as occurring in some cases in connexion with brachymeiosis, was 
seen in the prophase of the third division nor indeed at any stage subsequent 
to the first division. In the third division, the spindle is generally orientated 
at right angles to the long axis of the ascus, but not invariably so. During 
the metaphase of this division the chromosomes are arranged on the equa¬ 
torial plane of the spindle in the manner usual in karyokinesis (Fig. 42). 
The anaphase is represented in Fig. 43, and the telophase in Fig. 44. In 
reference to Fig. 43 it should be stated that the preparation was made from 
material which had been lying damp in the laboratory for some days, whereas 
