hargitt: pennaria tiarella and tubularia crocea. 169 



split longitudinally, beginning at one end, though the evidence is not 

 sufficient to make this certain. After the division has been completed 

 the parts appear to arrange themselves in the form of an x. The 

 final disposition of these bodies or their parts was not determined, 

 since the stages immediately following are lacking in my preparations. 



An accurate count of the chromosomes was not possible, because, 

 unfortunately, in every case the chromosomes occupied two or three 

 sections. By careful focussing to determine which had possibly been 

 divided in sectioning and were therefore to be found in two sections, 

 and by making accurate camera drawings of all the chromosomes of 

 the two sections possibly involved, and superposing them, it has been 

 possible to make a reasonably safe estimate of the number of separate 

 elements. In one egg there were clearly ten. Another case, while 

 not so satisfactory, makes it safe to say that not more than ten are 

 present. By a similar method of estimate a third case gave eleven, 

 and a fourth thirteen, as the probable number of separate chromosomes. 

 A comparison of the Figures shows clearly that some of the chromo- 

 somes are beginning to split, so that probably what appear to be 

 separate elements are really moities of a single body. Just how many 

 are split sufficiently to give this appearance I could not determine. 

 In Figure 11 the splitting has proceeded so far, and the chromosomes 

 are so closely massed, that no safe estimate of the number of chromo- 

 somes could be based on this egg. On the whole, the evidence seems 

 to point to ten as the probable nimiber of chromosomes in the spindle. 

 This is a smaller number than occurs in the cleavage spindle, so that 

 there is probably a reduction in number before this stage is reached. 

 The accurate determination of the number of chromosomes in the 

 second cleavage spindle is, however, more difficult than in the matura- 

 tion spindle, so that I cannot state with any degree of confidence the 

 number of chromosomes which occur in the former. The reduction 

 had already occurred before the first maturation spindle was formed, 

 but as to where and when, I have no direct evidence. 



The spindle, at an earlier period nearly tangential, now assumes a 

 radial position. The asters, which were smaller during the tangential 

 position than when first formed, entirely disappear from both poles. 

 The centrosomes, however, remain, and the sjiindle then appears as 

 shown in Figure 12. The chromosomes here are somewhat scattered, 

 and an accurate count is not possible. Near the more superficially 

 located pole, the chromosomes seem to have become massed together 

 and to have left their normal place, being at one side of the spindle, 

 with which, however, they are still connected by fine filaments. The 



