240 



IV. THE PRINCIPLES OF LIFE PHENOMENA 



may have each site of determination. Mendel's laws of inheritance 

 can be well explained by this concept. 



However strong the reversibility of the protoplasm structure may 

 be, the pattern will more or less be damaged when the protoplasm is 

 repeatedly altered in its structure by various stimuli. The pattern 

 thus damaged will be repaired by genes which are always able to 

 retain the original pattern. 



Gene I 



Gene II 



Gene III 



[Dominant • 



'Recessive ,' . 



I Dominant ' A __ '..■ 



I Recessive ,-'"." — 1~. >^ -~""^n!^ . 



[ Dominant ' A . -' 



' Recessive r~rC'~-~ ^ 1"Z , 



Cytoplasm 



Fig. 23. Diagram of genes. 



Chromosomes as above suggested may be coagulated aggregates of 

 genes of relatively similar structures, so that in the chromosomes the 

 active groups of genes may be present in a folded state. Accordingly, 

 in this state genes may be unable to accomplish their function, which 

 may develop only when the coagulation is solved and gene particles 

 are set free. This may occur at a certain stage of the cell division, 

 at which nuclear masses are mixed with the cytoplasm. 



If genes always exerted their strong structural influence upon 

 the cytoplasm, the latter would be unable to change freely its struc- 

 ture, and accordmgly the exhibition of various vital functions would 

 become impossible which must only be accomplished by movement of 

 the protein molecules constituting cytoplasm. 



It is said that chromosomes are present as such only at a certain 

 stage of cell division, in the living interphase nucleus being optically 

 homogeneous, and that chromosomal structures appear only after 

 injury or treatment with histological fixations ; in the living nucleus 

 the chromosomes are in a greatly extended state, filling the nucleus 

 homogeneously and upon injury the chromosome condenses and becomes 



