AS THE ELEMENTAL GERM OF AN ORGANISM 345 



reasoning, and which in consequence could neither be verified by 

 observation nor developed further. 



In order to establish the hypothesis, that the nucleus is the 

 transmitter of the hereditary elemental germs, four points have to 

 be considered : 



1. The equivalence of the male and female hereditary masses. 



2. The equal distribution of the multiplying hereditary mass 

 upon the cells, which are derived from the fertilised ovum. 



3. The prevention of the summation of the hereditary masses. 



4. The isotropism of protoplasm. 



1. The Equivalence of the Male and Female Hereditary Masses. 

 It is evidently true, and hence must be accepted as an axiom, that 

 the egg and sperm cells are two similar units, each of which, being 

 provided with all the hereditary properties of its kind, transmits 

 an equal quantity of hereditary material to the offspring. The 

 offspring is in general a mixed product of both its parents ; it 

 receives from both father and mother an equal number of idio- 

 blasts, or active particles, which are the bearers of hereditary 

 attributes. 



However, it is only in the lowest organisms that the sexual 

 cells resemble each other in size and composition ; in the higher 

 organisms, they present in both respects the greatest differences, 

 so that in extreme cases an animal spermatozoon may be even 

 smaller than the hundred-millionth part of an egg. It is, however, 

 inconceivable, that the carriers of the elemental germs, which, 

 a priori, must be assumed to be equal both as to number and 

 attributes, can present such differences in their volume. On the 

 contrary, the fact that two cells, which are quite different as 

 regards mass, can possess equal hereditary potentialities, can be 

 easily explained by the assumption, that they may contain at the 

 same time substances of very different hereditary value, i.e. for 

 idioblastic and non-idioblastic substances. 



We must, therefore, endeavour to find this idioplasm in the egg 

 and spermatozoon, and to isolate it from the other substances. 



First of all, there is no doubt that the reserve materials fat 

 globules, yolk platelets, etc., must be included in the category of 

 germ substances, which are useless as regards heredity. But 

 even if we discard these, the egg and sperm cells still remaiu. 

 unequal, as regards the quantity of their other constituents. 

 For the protoplasm which is present in a large egg-cell, even 

 after all the contents of the yolk have been abstracted, is much 



