302 THOS. H. MONTGOMERY, 



Each univalent chromosome of a pair forming a bivalent loop of 

 the nucleus, undergoes important changes during the synapsis stage. 

 It continues to elongate and its contours become more uneven and 

 roughened (Figs. 56, 58, 69) ; this is the commencement of the process 

 of gradual decondensation of the chromatin. Next or synchronously, 

 for there appears to be no very definite sequence in these stage since 

 all the chromosomes do not seem to pass through them simultaneously 

 nor in exactly the same order, the chromatin assumes a more or less 

 monilated appearance, each chromosome then looking like a row of 

 irregular chromatin beads (Figs. 64—67, 70, 71, 74). Then the 

 chromatin granules (they are too large and irregular in size to be 

 called microsomes) separate from one another, but remain connected 

 together by a linin thread which is evidently the persisting part of 

 that original spirem thread forming the matrix of the chromosome 

 (Figs. 64 — 68, 70 — 84). Simultaneously occurs a flattening of these 

 granules, the flattening at first generally appearing to lie in the plane 

 joining the two arms of the V-shaped bivalent chromosome (Figs. 65 

 67, 70 — 74, 76 — 81, 84). Occasionally one finds very elongated, at- 

 tenuated chromosomes in the early synapsis (Figs. 68, 75, 76), but 

 on account of their great infrequency they cannot be considered to 

 represent a particular stage of the chromatin arrangement, but rather 

 a departure from the general condition ; with such cases should not be 

 confused already flattened chromosomes seen from their narrow edges. 



The beaded appearance of the chromosomes is somewhat the 

 same as the arrangement of the chromatin in the previous dense 

 spirem stage (Fig. 3, Plate 19). The chromatin granules vary con- 

 siderably in form and volume as the figures show. The segmentation 

 of the chromosome into the component granules does not take 

 place simultaneously on all portions but occurs at the central end 

 usually last. This might speak for a certain degree of independent 

 action upon the part of the granules. Further, these and other pro- 

 cesses still to be described do not proceed simultaneously for all the 

 chromosomes of one and the same nucleus: this points to a certain 

 individuality or independence upon the part of the chromosomes. The 

 first chromatin granules of a chromosome to segment oiî, or some of 

 them, are often larger than the ultimately formed granules, and then 



true, then mitosis may be looked upon as a provision for nuclear ex- 

 cretion as well as for cell division; and quite in line with this is the 

 fact that in mitosis the chromatin frees itself of waste products, i. e. 

 performs an act of excretion, in becoming pure nucleic acid. 



