196 Mr. C. F. U. Meek. The Ratio between Spindle 



Conclusion. 



Whether the connection suggested between spindle length and cell volume 

 in the metaphase is likely to be established or not is impossible for us to 

 say : the proposition that I have put forward is at present entirely specu- 

 lative. But the results of research have shown that at the stage in question 

 the ratio between spindle lengths is approximately the same in the spermato- 

 cytes of Helix pomatia, For -ficula auricularia, and man — organisms representing 

 three phyla of the animal kingdom. 



Moreover, consideration of the lengths found in these organisms proves 

 that the length of the spindle in the rnetaphase cannot be correlated with 

 the volume of the chromatin. This is important ; for in an earlier paper 1 

 have produced evidence to show that increasing somatic complexity is 

 accompanied by increase of chromatin volume in the cell. 



The failure of current theories of mitosis is largely due to the absence of 

 data from which to draw conclusions ; and, since either proof or disproof 

 of my proposition must constitute a new generalisation, I intend to carry 

 out further and similar cytometrical investigations, of which the results will 

 appear in subsequent papers. 



Summary. 



1. The length of the mitotic spindle, i.e. the distance between the centro- 

 somes, is 15"3 n at the conclusion of each primary spermatocyte metaphase 

 of Helix piomatia. 



2. The length of the mitotic spindle is 12'1 //, at the conclusion of each 

 secondary spermatocyte metaphase of Helix pomatia. 



3. The ratio between the lengths of the mitotic spindle at the conclusion 

 of the primary and secondary spermatocyte metaphases is approximately 

 the same in Helve pomatia, Forficula auricularia, and man ; and, since these 

 ratios are either identical or almost identical with the ratio between the 

 radii of two spheres of which the relative volumes are the same as those of 

 the cells in question, connection may exist between spindle length and cell 

 volume at this stage. 



4. A comparison of mitotic figures in Helix 'pomatia, Forficula auricularia, 

 and man proves that the length of the spindle in spermatocyte metaphases 

 cannot be correlated with the volume of chromatin in the cell. 



