DOMAIN OF EVOLUTIONARY HYPOTHESIS 99 



be permanently together in different cells of the same 

 organism and stand obviously in the closest connection 

 with the separative function of the separate organs ; 

 they may arise successively in one and the same cell, 

 according to varied functional conditions for instance, 

 times of rest and activity. This applies also to the 

 structure of the nuclear substance. 1 



According to the latest views of the study of the cell 

 we cannot speak of ' organs ' of the cell in the sense of 

 formations permanently existing and indispensable for 

 definite objects (e.g. cell division). That is true for 

 the cell skin, the centrioli, the ' chemical central-bodies/ 

 the nucleoli, and the rest of the included constituents, 

 and even for the nucleus. It is no longer correct to 

 refer to the nucleus, in the definition of the cell, as one 

 of the equivalent parts of the rest of the cell contents. 

 The nucleus does not appear at all in an enclosed bladder 

 in many unicellular organisms, but only the so-called 

 nuclear substance ; during each cell division it is 

 perfectly dissociated individually, but it is not essential 

 that it has a definite structure. The cell is therefore 

 that more or less exclusive and independent mass of 

 vivified matter in which alone the vital functions 

 are exercised. The cell assimilates, the cell divides 

 itself, etc., the nucleus and the centrioli being only 

 integral constituents of the total mass. Wilson 

 expresses this as follows : e A minute analysis of 



1 St. Maziarski : Sur les changements morphologiques de la structure 

 nucleaire dans les cellules glandulaires, in Archiv fiir Zellforschung, IV, 

 Leipzig, 1910. p. 443. 



H 2 



