3io 
Mottier . — The Development of the Heterotypic 
Methods. 
All material was fixed in chrom-osmic-acetic acid, after the formula 
published by the writer in 1897. Both the triple and iron-haematoxylin 
stains were used. In so far as pollen mother-cells are concerned; the triple 
stain of anilin safranin, gentian violet, and orange G is superior when 
all stages of mitosis are concerned. The iron-haematoxylin is very valuable 
in the differentiation of the chromatin during the prophases. In prepara- 
tions stained by the iron-haematoxylin, counter-staining with eosine, 
orange G, gentian violet, &c., was followed for a time, but as no special 
advantage could be observed in the use of the counter-stain, this part 
of the process was finally abandoned. Preparations of almost every stage 
of the process described in this paper have been made in duplicate, one-half 
of the slides stained with the triple, the other by the iron-haematoxylin. 
In this way one stain serves as a control for the other. 
From the Resting Nucleus to Synapsis. 
Podophyllum. The developing anthers of Podophyllum were examined 
during the autumn and winter in order to determine the nature of the 
chromatin in resting nuclei in the cells of both the sporogenous and purely 
vegetative tissues. In stamens fixed in early October; all stages of mitosis 
are to be seen in the cells that are to give rise to the pollen mother-cells, as 
well as in purely vegetative tissue. At this time of the year, the pollen 
mother-cells were not differentiated, at least, in all material examined. In 
stamens fixed January 20, the pollen mother-cells were. still undifferentiated, 
and about all nuclei were in the resting condition. A careful study of 
material collected at the dates just mentioned and in the following spring 
did not reveal any disposition of the chromatin into sixteen masses or 
lumps that might be regarded as representing the somatic chromosomes. 
As will be shown below for the pollen mother-cells, the chromatin of the 
resting nuclei exists in masses or lumps of varying sizes, and connected 
into a network by slender threads composed chiefly of linin. The number 
of chromatic masses was always greater than the number of somatic 
chromosomes. In fact, it is not possible to determine the exact number of 
these lumps, for they vary greatly in size, and three or more masses are 
frequently so connected by thick strands that it is not possible to know 
how many lumps each of such masses really represents. Frequently, in 
both sporogenous and purely vegetative cells of an anther, the resting nuclei 
will present the chromatin in rather fine granules uniformly distributed 
within the nuclear network. This finely granular condition of the chromatin 
in resting nuclei is also met with in the pollen mother-cells. In all cells 
showing such a distribution of the chromatin, fixation seems perfect; and it 
