CHROMx\TIN — DEVELOPMENT AND HEREDITY 233 



in the strange environment of the Fundulus egg cannot be char- 

 acterized justly as 'normal.' All of her drawings of the hybrids 

 show laggmg of the chromosomes in the anaphases, which in 

 itself is a marked irregularity. It is quite conceivable that a 

 slight lagging may not preclude normal division, but that such 

 a condition as her figures 12, 17, and 19 show, always leads to an 

 equal distribution of the chromatin to the two poles of the spindle 

 is doubtful. The altered form of the Ctenolabrus chromosomes 

 is difficult to interpret. At first it seemed that it might be 

 regarded as a sign of degeneration, but, after examining some of 

 the same hybrid eggs in which shorter Ctenolabrus rods are found 

 that are quite normal in appearance, it is evident that, if degenera- 

 tion does occur, it does not affect all of the chromosomes. It was 

 not my intention to make an extended study of this cross, there- 

 fore I preserved very little of the material, but such as I have 

 presents a few facts which seem worthy of mention, since they 

 give evidence of abnormal mitoses occurring in these hybrids. 

 From the following description it will be seen that these abnor- 

 malities take the form of an exaggerated lagging of the chromo- 

 somes during division, which probably results in the elimination 

 of whole chromosomes from the nucleus. 



Figures 18 and 19 are sections of the two anaphase spindles 

 of one egg. The sections are oblique to the axis of the spindles, 

 but the corresponding poles are lettered alike in each drawing 

 so that one can obtain a fair idea of the nature of the elements 

 gathered at either pole and scattered between. Definite, blackly 

 staining bodies occur at the equatorial plate of each spindle, 

 although the mass of this material is greater in the spindle of 

 figure 18 than in the other. These bodies have a very similar 

 appearance to that of the yolk bodies scattered through the 

 cytoplasm. They have the same homogeneous consistency, 

 the smooth contour, and in some instances the spherical form. 

 Slender protuberances from these masses resemble the ends of 

 chromosomes. Whether the other end is fused with the larger 

 body or is merely hidden by it, is impossible to determine. Nor- 

 mal Fundulus chromosomes and some apparently normal Ctenola- 

 brus chromosomes appear at the poles. Some abnormally thick- 

 ened bodies are present which suggest undivided chromosomes. 



