iS . EISEX. [Vol. XVII. 



permanent organizations. As regards the nature of the para- 

 chromatic granules we do not know anything with certainty, 

 but it seems probable that they are of great importance. 



The C/u'otnioles. — The chromioles are the smallest visible 

 organized parts of the chromosomes. They undoubtedly con- 

 stitute the most important parts of the chromosomes, the fun- 

 damental elements which the other parts of the chromosomes 

 only serve to nourish and to preserve. If we view a perfectly 

 fixed and stained chromosome during any of the mitotic 

 phases, we find that it is not a homogeneous body, but one 

 that shows considerable differentiation in a regular manner. 

 We first observe that the outline or margin of the chromosome 

 is not an even one, but one which shows deep indentations of 

 even size and number. These indentations are so arranged 

 that the chromosome appears to be more or less beaded ; that 

 is, a convexity on one side corresponds to a convexity on the 

 other side, and a concavity similarly corresponds to a concav- 

 ity. We moreover find that these beads are of a constant num- 

 ber, at least in chromosomes of average size. A chromosome 

 of Batrachoseps in the beginning of the metaphase of an auxo- 

 cyte contains just six such beads, the beads being identical with 

 chromomeres. A closer study of one of these chromomeres 

 shows that they are not of a homogeneous structure, but that 

 each one of them contains several interior round granules, sur- 

 rounded by an apparently homogeneous substance. These 

 granules, for which I propose the name of chromioles, are 

 of globular form and of equal size (Figs. 53, 54, 112, 

 120, etc.). I need not point out the necessity of having the 

 chromosomes properly stained. If too dark, the chromioles 

 will not be seen, but the whole chromosome will appear as a 

 solid homogeneous mass of chromatin. Even when the chro- 

 momeres have been so fused together that the margins of the 

 chromosomes are only slightly wavy, the chromioles are yet 

 distinct enough not only to be seen, but under favorable cir- 

 cumstances to be actually counted. A very good view is had 

 of the chromioles in the chromosomes, of which Fig. 112 gives 

 as correct a representation as it was possible to make. Of 

 course, instances where chromioles are as distinct as these 



