244 THE GERM-PIASM 



must therefore suppose that the fertilised ovum from which the 

 child arose contained a very similar combination of ids and 

 idants to that which controlled the ontogeny of the father. It 

 must therefore be possible, and cannot be altogether a matter of 

 chance, that the germ-cell of the father contains these paternal 

 or maternal idants, — or, in other words, almost precisely the 

 same ids as those which directed the development of the father 

 or mother, arranged in almost the same order. This is only 

 conceivable, it seems to me. if the combination of ids into idants 

 usually, at any rate, persists even during the disintegration of the 

 latter in the nucleus. 



Many recent observations support this conclusion, inasmuch 

 as they show that fine threads of • linin ' connect the individual 

 microsomata (ids), even when the idant has apparently undergone 

 disintegration. In fact. Dr. Otto vom Rath * has just shown that 

 such connecting threads even extend between the idants. It is 

 therefore probably not too bold an hypothesis to assume the 

 existence of such an arrangement for connecting the ids together. 



I am therefore of the opinion that the idants only apparently 

 undergo disintegration into granules during the ' resting-stage ' 

 of the nucleus, and I agree with van Beneden and Boveri in 

 considering the idants to be essentially permanent structures. 

 I do not. however, as already mentioned, wish this statement to 

 be taken too literally : it must not be supposed that the structure 

 of an idant must always remain the same tliroughout all genera- 

 tions, or that the reconstioiction of an idant after its disintegra- 

 tion must in all cases result in the ids being rearranged in the 

 same order. I imagine, on the contrary, that deviations from 

 the original serial arrangement frequently occur in the ids. The 

 fact of the constant change of individuality and non-recurrence 

 of the same individual which can actually be observed in the 

 human race in the course of generations, indicates, in my 

 opinion, that an occasional change of the ids within the idants 

 can take place in the course of generations, although this does 

 not occur every time the idants are reconstructed. 



If this is the case, and essentially the same idants persist 

 during ontogeny from the fertilised ovum to the germ-cells of 



* ' Zu-r Kentniss des Spermatogenese von Grylloptalpa vulgaris.' — Arch, 

 f. Mikr. Anat., Rd. 40, p. 120. 



