A critical study of the cytology of Crepis virens. 
111 
experienced in ascertaining that a particular telophase is in fact that 
of a last archesporial division, and not one of a progressive series. In 
Order therefore, to obviate error as far as possible, flower heads were 
selected, some of whose buds had pollen mother-nuclei in presynapsis 
and synapsis. Buds can be found in such an inflorescence whose anthers 
are so far mature that they have cut off the four outer layers of cells 
(i. e. epidermis + tapetum), yet whose sporogeneous nuclei are still divid- 
ing somatically. Such nuclei are completing their last archesporial divi- 
sion, and the telophases will pass into the resting state preceding the 
heterotype prophase. Buds of this character have been studied through 
a series of transverse sections, and the various stages are represented 
by PI. VIII, fig. 31, to PI. IX, fig. 41 inclusive. 
The true sequence of the stages of the passing of the telophase into 
rest may be traced by foUowing out the obliteration of the spindle 
fibres ; the decrease in the number of the deeply staining chromatic bodies 
in the cytoplasm, indicative of a recent division; the enlargement of the 
area of the loculus, accompanied by a sharp definition of the sporogeneous 
tissue distinguishing it from the surroimding parietal layers; and, finally, 
the concentration of the chromatic contents of the nucleus into fewer 
and more definite aggregations. 
From the telophase of the last archesporial division to the with- 
drawal of the nuclear contents into sjmapsis, only entire nuclei have 
beeil studied and chawn. 
In those nuclei whose linm is arranged peripherally, the Strands 
at the extreme upper and lower focus have been omitted, as it was found 
that they soniewhat obscured the detail of the nuclear contents. Other- 
wise an attempt has been made to represent actual portraits of entire 
nuclei. 
Telophase of the last archesporial division. 
In late anaphase the chromosonies are massed together and the spindle 
fibres are replaced by a reticulate cytoplasm (PI. VIII, fig. 30). The 
chi-omosonies subsequently, once more separate from one another and 
fragment ; a limiting nuclear membrane fornis ; and generally two nucleoli 
make their appearance. Few data have been acqub'ed regarding those 
stages concerned with the inirnediate fragmentation of the chromosonies, 
for the staining reaction during this period is diffuse, and obscures the 
course of events. By the time, however, that the cell wall is laid down 
between the daughter nuclei, the chromosomes have usually resolved 
themselves completely into rounded chromatic granules united by fine 
