KARYOKINESIS 



95 



It lias been found in our experiments that in order to obtain 

 the regular division of the artificial nucleus represented by the 

 intermediary drop, the latter must have an osmotic pressure 

 slightly below that of the plasma. This leads to the supposi- 

 tion that a similar condition must obtain in the natural cell. 

 It may be noticed, moreover, that the grains of pigment follow 

 tlie direction of the flow of water, being carried along by the 

 stream. This would appear to show that the nucleus of a 

 natural cell has also a molecular concentration less than that 

 of the plasma — a result either of dehydration of the plasma, 

 or of some diminution in the molecular concentration of the 

 nucleus. 



Other phenomena of karyokinesis may also be closelv 



Fig. 33. — Equatorial crown produced 

 by diffusion. 



imitated by diffusion. For instance, in the diffusion prepara- 

 tion we notice at each extremity of the equator a V-shaped 

 figure with its apex towards the centre, corresponding exactly 

 to what in natural karyokinesis is called the equatorial crown. 



We may also produce diffusion figures of abnormal karyo- 

 kinesis. Fig. 34 represents such a form, a triaster produced 

 by diffusion. 



Artificial karyokinesis may also be produced by hypotonic 

 poles of concentration — that is to say, when the central drop 

 representing the ovum is positive and the lateral drops 

 representing the centrosomes are negative with respect to the 

 plasma. In this case, however, the resemblance to natural 

 karyokinesis is less perfect. 



