348 Mottier . — On the Prophases of the Heterotypic Mitosis in 
very closely related, stages is evidenced by the size of the cells and by 
the developmental stages of the ovules (Figs. 9 a and 10#). There re- 
mains to be considered the probable effect of the reagents as being 
responsible, at least in a measure, for the more slender spirem and the 
wider divergence of its longitudinal segments, — a suggestion expressed in 
a preceding paragraph and in the writer’s former publication. From the 
ovary in which Fig. 10 is found, a part of the ovule as well as the wall 
of the loculus was cut away ; consequently the osmic acid of the fixing 
fluid had freer access to the cell (Fig. 10a). While the author is strongly 
of the opinion that the fineness or coarseness presented by the chromatin- 
granules in the case of the resting nucleus in question (Figs. 1 and 2) 
is probably due to the fixing fluid, yet he feels that he cannot speak 
with positive assurance until experiments now in progress are completed. 
However, this is certain : no matter how widely, or for whatever length, 
or lengths, the longitudinal halves of the chromatin spirem may separate 
and diverge from each other at this stage, they soon come together 
again and adhere or unite so closely that, apart from rare exceptions, 
the double nature of the cord is quite obscured at the time of the looping 
or approximation of parallel parts to form the bivalent chromosomes. 
Fig. 11 represents the stage of looping and the approximation of parts 
of the spirem to form the bivalents just before the cross segmentation. 
The number of loops is not equal to the number of chromosomes, and it 
has never been contended by the writer that such is the case. The fact 
that loops frequently occur may have little or no importance theoretically, 
but that the two members of a bivalent chromosome are brought together 
side by side by such a looping is conclusive evidence that these two 
members were placed end to end in the spirem, no matter whether the 
spirem was continuous, or interrupted, or ‘ heterogeneous ’. In the case of 
Fig. 11 a, the inner integument of the ovule has grown up beyond the end of 
the nucellus to form the micropyle. In this respect there is some variation, 
as the nucleus may reach the stage in question while the integuments are 
shorter. From this time on the segmentation of the spirem and the further 
behaviour of the bivalents are quite similar to those processes in the pollen 
mother-cell as described in my former paper, so that a further description 
and a duplication of illustrations seem unnecessary. 
Summary and Conclusions. 
From the foregoing it will be seen that the heterotypic mitosis in the 
megaspore mother-cell of Lilium agrees essentially with that mitosis in the 
pollen mother-cell as described by the author in his former publication 
(Mottier, ’ 07 ). In the micro-, as well as in the megaspore mother-cell, the 
chromatin in the resting nucleus, or in an early pre-synaptic stage, was 
either in the form of fine granules or larger and coarser lumps. It was 
