240 EDITH PINNEY 



from polyspermic eggs of this and other crosses seems to justify 

 such a conchision. At any rate, in this event of abnormal 

 cytoplasmic division two quite 'normal' anaphase figures appear. 

 These are shown in detail in figure 35 and 36. As in mono- 

 spermic eggs the morphological characters of the chromosomes 

 of the two species persist, there is no lagging on either spindle 

 and the cleavage rate of the egg is not changed. 



Occasional evidences of lagging chromosomes are met in this 

 cross. Figure 37 represents a two-celled egg in the telophase 

 of the second cleavage which showed lagging nuclear vesicles. 

 Only two such instances were observed. The only other case 

 in which lagging was observed in these early stages was on a 

 slide among sections of normal and polyspermic eggs. The 

 normal eggs were two-celled, the polyspermic eggs usually four- 

 celled. The egg in which lagging occurred was apparently a two- 

 celled egg which was in the anaphase of the second cleavage. A 

 strand of chromatin lay stretched across the first cleavage plane 

 and was connected by astral fibers with both spindles. That 

 this chromatin had been left in this position at the end of the 

 first cleavage was apparent from the fact that it had interfered 

 with the normal extension of the cell wall which usually com- 

 pletely separates the first two blastomeres. 



Another feature noted in the same egg, and met occasionally 

 in this as well as in other crosses, may be described here. In 

 the third cell of this egg two asters are present. Whether these 

 previously formed a spindle is uncertain. The cytoplasm in the 

 region between them has a coarser granular appearance and stains 

 more deeply than the same region in normal Ctenolabrus eggs. 

 If chromatin were present here it has been dissolved, but the cause 

 of such an occurrence is still obscure. Figures 38 and 39 show 

 the spindles from a two-celled hybrid egg in which the same 

 granular condition of the cytoplasm in the equatorial region 

 appears. All of the chromosomes present in the egg are drawn 

 in these figures. It is evident that some are missing and, since 

 there is a decided lack of hook-shaped chromosomes and a pre- 

 dominance of long Fundulus elements, the obvious conclusion 

 is that some of the chromosomes of the egg are missing. This 



