66 Proceedings of the Royal Physical Society. 



same stamp of heredity, and the different parts they play in 

 the life of the group must depend, on the one hand, on the 

 kind of metabolism they are forced to undergo by their 

 environment, the effect of the rest of the body upon them, 

 and, on the other hand, on the tendency of all the cells 

 derived from the initial cell to develop along certain lines 

 marked out by heredity. 



Each cell, by specialisation, gives preference to a certain 

 function, or set of functions, which were dormant in the 

 mother-cell, but only capable of perfect action by gradual 

 obliteration of the many other functions originally present 

 in a dormant condition. The functions are thus limited in 

 number by specialisation, but those that are left are rendered 

 more capable. Arrest of specialisation, through the form of 

 nutrition or otherwise, may leave the cell with many func- 

 tions lying in a dormant condition, capable of specialisation 

 if necessity calls for it, when the environment of the body 

 will force the cell to take up the position required of it. 

 On the other hand, should the cell be not too far advanced 

 in specialisation, and therefore have retained the greater 

 part of the functions of the individual in a dormant state, 

 it may, through change in the nutrition, or by being com- 

 pounded with other cells which help to supply its deficiencies, 

 be forced to begin a new development on its own account, 

 thus reconstructing the whole individual again. The capa- 

 bility of regeneration of the whole individual, as in regenera- 

 tion of parts, would, in fact, seem to depend, in some cases, 

 on a sufficient number of cells being left in mutual co- 

 operation. 



The following remarks from "The Cell in Development 

 and Inheritance " (3) may here be quoted : — '• It is but a step 

 from this to the very interesting suggestion of Driesch, that 

 the nucleus is a storehouse of ferments which pass out into 

 the cytoplasm, and there set up specific activities. Under 

 the influence of these ferments, the cytoplasmic organisation 

 is determined at every step of development, and new condi- 

 tions are established for the ensuing change. This view 

 is put forward only tentatively as a ' fiction ' or working 

 hypothesis ; but it is certainly full of suggestion. Could we 



