EFFECTS OF AMPHIMIXIS ON THE GERM-PLASM 243 



substance, and only recombine to form nuclear rods when the 

 second division begins to take place. This process of disin- 

 tegration and subsequent recombination of the idants is repeated 

 every time a cell is formed by division during ontogeny, and 

 thus it is impossible to decide whether a certain idant of any 

 particular cell is derived from the father or from the mother. And 

 further, we cannot even ascertain with any degree of certainty 

 by mere observation, whether the idants of the subsequent cells 

 are the same as those of the fertilised egg-cell, — that is to say, 

 whether they contain the same kinds of ids in the same order. 

 It is very possible that the ids may become entirely separated 

 from each other whenever the idants undergo disintegration, and 

 then become arranged in some other order subsequently. The 

 number and nature of the ids contained in the entire idioplasm 

 would then certainly remain the same as before, but the indi- 

 vidual idants would differ, because the combination of ids would 

 be different. It would then be immaterial whether the idants 

 on the right were separated from those on the left in the reducing 

 division, or whether the halving of the number of idants were 

 effected in some other way ; all the idants would consist of new 

 combinations of ids already present, and their combination 

 would necessarily differ completely from that of the idants of the 

 fertilised egg-cell, which is almost always separated by a number 

 of cell-generations from the new germ-cells, in each of which a 

 rearrangement of the ids must have taken place. The removal 

 of entire idants in the reducing di\'ision would obviously there- 

 fore be unnecessary, for the mere qualitative division of the 

 whole of the idioplasm into two halves would be sufficient for 

 the purpose. 



As, however, the reducing division actually consists in the 

 removal of half the number of idants, and as, moreover, this 

 division is, as we shall see, a double one, I conclude that the 

 disintegration of the idants after every nuclear division is only an 

 apparent one, and that the separate ids of the idant, on the con- 

 trary, remain connected together by fine threads of the cementing 

 substance, or • linin ' ; and at the approach of nuclear division, 

 they become rearranged in the same order as before. 



That this is the case may be concluded from certain phenom- 

 ena of heredity; a child, for instance, not unfrequently takes 

 after one parent, e.g., the father only, or at any rate to such an 

 extent that the resemblance to tlie mother is unnoticeable. We 



