320 Mottier . — The Development of the Heterotypic 
In anthers, containing the stage of Figs. 25 and 26, some of the pollen 
mother-cells fix and stain in such a manner that the chromatin and linin 
make-up of the thread is very clearly shown. For example, it is found 
that in one end of the anther, the cells will so differentiate in staining with 
either the triple or the iron-haematoxylin method, that the chromomeres 
are brought out very distinctly, while in the remaining part of the anther 
the stain is held more uniformly by the thread, and the differentiation into 
linin and chromomeres is not so apparent. Figs. 25 and 26 may be found 
in the same section of a loculus. In Fig. 25, the safranin washed out of 
the thread almost completely, and, as a result after staining with gentian 
violet, the linin remained colourless or nearly so, and the chromomeres blue. 
In Fig. 2 6, which is typical of all remaining nuclei in the loculus, the 
spirem retained the safranin more uniformly throughout, and the result was 
a more uniform thread, showing, however, the longitudinal fission, and the 
chromomeres in certain parts as a series of small lumps. As stated, the 
same differentiation is obtained by the use of the iron-haematoxylin stain. 
Whether these nuclei are to be regarded as slightly different stages, or as 
representing conditions in which the fixing fluid preserved the structures 
in such a manner as to render chromatin and linin capable of retaining the 
stains in a different degree, is a question. It not infrequently happens that, 
in a number of cells in one end of the loculus, the chromatin will differentiate 
as shown in Fig. 25, but in all other cells of the same loculus the condition of 
Fig. 26 prevails. However, as we know that nuclei in the same loculus are 
frequently in different mitotic stages, the fact that some of the nuclei in the 
end of an anther differentiate as in Fig. 2 5, and others as Fig. 26, may be 
due to differences in the stage of mitotic development. In the cytoplasm 
of these cells there is also some difference in appearance. The cells showing 
the nuclear structure of Fig. 25 have apparently a more finely granular 
cytoplasm, in which the fibrillar nature is not as clearly brought out as in 
those cells with nuclei of the structure shown in Fig. 26. In neither case, 
however, was there anything that could be looked upon as bad fixing. 
So far as known to the writer, the true nature of the chromatin thread 
immediately following synapsis can be more clearly demonstrated in 
Lilium than in any other plant. Here it is shown with sharply defined 
clearness that the spirem consists of what is almost universally known as 
linin, in which are held the granules equally well known as chromatin. 
The chromatin granules are arranged, for the most part, in two rows, which, 
the writer believes, is the result of a true longitudinal fission. Each 
granule is usually spoken of as a chromatin disk or chromomere. It is 
also evident that each chromomere is composed of a number of smaller 
granules. According to the writer’s interpretation, each chromomere is not 
in the form of a disk, and he desires to emphasize again, as he stated 
a number of years ago, that the spirem does not consist of alternate disks 
