Literanscli-kritisclic Rundschau. 375 



realised that they are the seats of like "charges" in respect of 

 electricity and of osmosis.) 



■'Anaphases " — the stages of the discession of the chromo- 

 somes from the equator — are rehitively rare in our specimens 

 in Proportion to other stages of mitokinesis ; and among, anaphases, 

 the later stages are themselves rare. On the centred force 

 hypotheses this scarcity of these stages in our preparations is 

 easy of explanation. For the attraction on the chromosorae is 

 a direct function of its proximity to the centrosome; and con- 

 sequently its speed of translation should increase until it comes 

 into actual contact therewith. Now in the case of intermittent 

 observations of conseciitive phases the chance of Observation of 

 a given phase is an inverse function of the speed which that 

 phase occupies. Thus, other things being equal, if as I write I look 

 out of window occasionally for a moment, I am much more likely 

 to see a slow cart than a swift automobile. When I first 

 consulted that great electrician the late Professor W. E. Ayrton, 

 about the interpretation of the cellfield, he suggested that the 

 centred force hypothesis would be supported by any evidence 

 that the chromosomes speeded up as they approached the centro- 

 somes, I went away sorrowing, for I could not see how evidence 

 on this point was to be obtained from our tixed specimens. It 

 was not tili long after that I saw that the scarcity of anaphases, 

 and the still greater scarcity of late anaphases, supplied just the 

 very evidence desiderated. 



We are entitled to say that Geigel's paper instead of 

 refuting the centred-force hypotheses has, if anything, advanced 

 their title to support. 



II. 



Geigel's second thesis deals with the formation of the 

 attractive eminence formed on the oosphere on the approach of 

 the sperm. This grows out vertically underneath the sperm, and 

 has the form of a mound with doubly curved sides, concave at 

 the flanks, but with the tip rounded of into a blunted cone, like 

 the top of a sugar-loaf. Geigel argues that if the formation be 

 due to loss of surface-tension of the skin-layer of the oosphere 

 induced by the approach of the sperm, the outline of the curve 

 should be a simple convex curve. Geigel has assumed a direct 

 physical effect, instead of a phy siol ogical response. 



