5.8 CENTROSOMES, SPINDLE AND ASTERS [CH. iv 



itself, rather than to be determined solely by the achromatic 

 figure 1 . It is possible, however, that this may be brought 

 into harmony with the conclusion that cytoplasmic division 

 is determined by the spindle and asters by means of 

 HERLANT'S observation that the length of the spindle varies 

 with the size of the nucleus. The cells with larger nuclei 

 would thus have larger spindles, and the daughter-cells 

 would therefore have larger cytoplasmic volumes. 



NOTE. While this book was in the press, the writer's attention was called to 

 a paper by JESSUP, BALY, GOODBODY and PRIDEAUX on "The electrical forces 

 of mitosis and the origin of cancer" (Biochem. Journ. iv. 1909, p. 191) in which 

 it is maintained that many of the phenomena of mitosis may be due to electrical 

 forces, and that the centrosomes at the two poles of the spindle may bear opposite 

 charges. They point out that just as an ionisable salt is dissociated in water into 

 positively and negatively charged atoms or radicles, so a complex of molecules 

 forming a colloid substance may be separated into portions bearing opposite 

 charges. " It would appear that in the configuration of the protein material we 

 have at hand all the necessary conditions for the establishment of such charges. 

 The NH CO linking which, from a physicochemical point of view is both 

 acid and basic in character, or, as usually called, amphoteric, possesses a residual 

 affinity of two opposite types, and it is in the existence of these two types that we 

 can obtain the mechanism for the establishment of electrostatic differences of 

 potential.... In an analogous fashion [to the ionisation of salts in water solution] 

 the cytoplasm can resolve a discrete molecule or complex of molecules of 

 amphoteric type into two oppositely charged portions. The cytoplasmic mass 

 can, by virtue of its two types of residual affinity, form loose compounds with 

 the two portions of the simpler compound. The lines of force between the 

 two will be weakened, and the two portions can be separated and become seats 

 of positive and negative charges respectively." It is suggested that the centro- 

 some divides in this manner into positively and negatively charged halves, that 

 some non-electrical force connected with cytoplasmic division carries the 

 centrosomes apart, and that the spindle arises by coagulation of cytoplasm 

 along the lines of force running between them. These lines of force will also 

 tend to coagulate colloid bodies lying between the poles ; to this tendency is 

 ascribed the condensation of the chromosomes in the nucleus. The condensed 

 chromosomes divide by the action of the same forces which previously caused 

 the division of the centrosome. These split chromosomes would be forced into 

 the equatorial plate of the spindle, and by the attraction of the centrosomes the 

 negatively charged half of each chromosome will travel to the positively 

 charged centrosome, and vice versa. It must be assumed that the charges are 

 such as completely to neutralise one another at the telophase of the division. 

 This hypothesis, though open to several of the objections which apply to 

 HARTOG'S "mitokinetism," has the advantage of not postulating any totally 

 unknown force. 



1 In this connection see also PAINTER, T. S. (1918). 



