340 
Fault . — The Cytology of 
disposition of the chromatin. It will be observed that the volume has 
diminished, and that the threads are thicker and more irregularly 
arranged. 
Up to this time a central body has not been conspicuous, though 
probably present as indicated in Fig. 44. But now it can be found without 
great difficulty, and as shown in Fig. 50 the chromatin threads are 
apparently connected with it. Such a phenomenon was first discovered by 
Harper (’ 05 ) in Phyllactinia . It will again be noted that the polarity 
of the nucleus with respect to the nucleolus is still maintained, in which 
phenomenon the linin threads already described may play some part, since 
they appear to converge at the side opposite the nucleolus and there stand 
in connexion with the central body. This stage (Fig. 50) is immediately 
prior to the first mitosis, and constitutes a part of its prophase. The 
number of chromatic threads is clearly four, and these are identical with the 
four chromosomes to be seen on the spindle. 
During all this time the nucleolus has been a very conspicuous organ. 
Each of the initial pair of nuclei contributed a large nucleolus, and these 
fused to form that of the definitive nucleus. Its growth throughout is 
steady and remarkable. In the later stages it becomes quite vacuolate and 
at times even somewhat honeycombed. During mitosis it steadily diminishes 
in size, but a portion of it still remains almost up to the time the daughter 
nuclei begin to form (Pis. XXXIX and XL, Figs. 42-54). 
The first spindle is in many respects a very interesting structure. It is 
clearly intranuclear and is terminated at both ends by an extranuclear 
disc-shaped central body, evidently the products of division of the pre- 
existing one already noted, from which stream out long astral rays. 
There are four elongated and curved chromosomes of unusual size for 
a fungus (Figs. 51-2). The achromatic portion of the spindle consists 
of two sets of fibrils, such as I have described in Hydnobolites , &c. (Faull, 
’ 05 ) — a central system of many rather closely packed threads, and an outer 
mantle system. The mantle rays bear the chromosomes and appear to be 
responsible for their transport to the opposite ends of the spindle. After 
the chromosomes have reached the poles of the spindle the central fibrils 
experience a great elongation, carrying the daughter chromatic elements far 
apart (PI. XL, Fig. 54). In some instances, not figured, the remains of this 
central spindle have been observed subsequent to the stage represented in 
Fig. 54, the fibres no longer separable, the whole thing resembling a coarse 
sharply defined dark cord, and irregularly wavy or crooked as though it had 
lost its former tension and was incapable of contraction. The daughter 
chromosome masses had probably moved slightly towards one another 
after the central spindle had fulfilled its function. This wide separation 
of the daughters of the definitive nucleus is a characteristic phenomenon of 
the first mitosis in every order of the sac-fungi. 
