i4(; 



Fig. 15. JMiase separation in tlie nncleus of frozen plant cells. (After 

 Matruc'hot and Molliard, 1902.) The chromatin is represented in solid black 

 masses. 



frozen controls (Fig-. 15, A), shows vacuolization in frozen 

 cells. The chromatin forms a network with the meshes 

 elongated in the direction of the vacuoles (Fig. 15, B). If 

 the nncleus is between two vacuoles, the pattern is then 

 bipolar (Fig. 15, B), if there is only one vacuole in the 

 neighborhood of the nucleus, the pattern is monopolar 

 (Fig. 15, C). The meshes fuse into larger masses at the 

 equator of the nucleus in bipolar systems and at the pole 

 opposed to the vacuole in monopolar ones. These masses 

 of cliromatin become more and more compact, the fila- 

 ments projecting from them thin out gradually (Fig. 15, 

 D) and finally there results (in bipolar systems), a crown 

 of chromatin at the equator of the nucleus, separating two 

 nuclear vacuoles which bulge out on each side (Fig. 15, E), 

 III the cells with more condensed contents (from micelles 

 and ovaries), the chromatin meshes are thicker, the vacu- 

 oles within the meshes occupy a smaller volume, and the 

 entire pattern is of a different type (Fig. 1-3, F). As to 

 llie cytoplasm, which is described as gramilai- in the nor- 

 mal condition, it l)ecomes spumous or spongy by vacuoli- 

 zation, after freezing. In general, in the cells studied by 

 Matruchot and Alolliard there was, on freezing, a separa- 



