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James R. Weir. 
in the gametophyte. This must remain somewhat problematical, 
however, as the number of chromosomes cannot be counted for 
either generation. 
Nuclear Division in the Uredine^e. 
Nuclear division in most of the cells of the Uredinese is of an 
exceedingly simple type. The nuclei according to Blackman 
(whether single or conjugate) lose their membrane, the nucleolus 
becomes extruded and the chromatin condensed into one or some¬ 
times two masses. A rudimentary spindle is sometimes formed 
and on this the chromatin becomes spread and is drawn apart into 
two or sometimes four pear-shaped masses which separate and 
form the daughter nuclei. In the paired nuclei of the sporophyte 
generation the stages of the division of the two nuclei are the same 
at all times in any given cell. This method of division is to be 
regarded as amitotic or, at least, a very greatly reduced form of 
karyokinesis. 
In the promycelium the two divisions are much more typical 
and compare closely with that which prevails in the higher fungi 
and algae and even in the higher plants. The work of Harper and 
Holden is probably the most exhaustive that has been accomplished 
so far in this field of research and their results will be given 
somewhat in detail. 
The resulting fusion nucleus is nearly spherical and occupies a 
position near the centre of the cell. The chromatin is arranged in 
rather dense masses. The first evident change which the fusion 
nucleus undergoes is a loosening up of the dense chromatin masses. 
The threads become definite in outline and are more readily traced 
(Fig. 13). Next they increase in thickness and sharpness of outline 
This is probably due to a shortening of the thread. Closely following 
this stage the nuclear membrane disappears and the spirem lies in 
a finely granular substance not sharply distinguished from the 
surrounding cytoplasm. The thread is seen now to have split 
longitudinally and in certain parts the daughter segments diverge 
widely while in others they are closely applied (Fig. 17). This 
phenomenon of the nucleus is rather interesting as it establishes a 
point of similarity in this division and the first or heterotypic division 
of the higher plants. The spirem now segments transversely into 
several pieces which later become arranged on the spindle as in 
more typical cases of mitosis. 
The stages in the formation of the spindle were not observed 
