INHERITANCE OF ACQUIRED CHARACTERS. 2'J'J 



that it is due to differential division of some cell constitaent. 

 This constituent cannot be either chromatin or lymph, and must 

 be the linin. We must therefore suppose that the linin of the 

 ovum is, in segmentation, divided differentially in the way 

 sketched by W'eismann for his germ-plasm. 



But what is the linin of the ovum? When we consider that 

 the distinctive character of each tissue is a linin compound, and 

 that the yolk is the distinctive character of the ovum ; that, 

 moreover, fibrillas are mostly absent from ova, we must con- 

 clude that the yolk is a linin compound of the ovum. 



The further course of events I imagine to be as follows : 

 The yolk, like all linin compounds, is irritable, and continually 

 some of it will be deprived of certain radicals and rise alcove 

 the heavier unaltered yolk, so that the first horizontal division 

 will be a differential division. After gastrulation the stimula- 

 tion of the inner cell-layer will be different, and another kind 

 of radical will be split off' from the yolk. This process will 

 'be continued until all the tissues have been formed and come 

 into function. As soon as this happens the lymph will contain 

 all the radicals necessary for the formation of yolk, and those 

 cells, which, on account of their ancestry — i.e., which have, during 

 the process of differentiation, retained certain necessary radicals, 

 will now select the lymph radicals required, and build up the 

 same 3^olk compound as was present in the previous generation of 

 germ cells. 



Imagine an ovum with yolk L A B C . . . . X Y Z. Let 

 this give rise to the tissues L A, LB, L C, etc. Let the func- 

 tioning of the tissue L A set free the radical A in the lymph, 

 whilst the enzyme chromatin, in the presence of other L A, re- 

 builds more L A from food radicals in the lymph. Let L G be 

 the linin of the germ cells, and let L G, if the necessary radicals 

 are available, be able to build up L A B C . . . . X Y Z again. 

 Now suppose the environment change'^ m such a wav that the 

 tissue L A. becomes changed to L(A+a) ; then the functioning 

 of that tissue will set free in the lymph ( A + a), and the gerni-ccU 

 linin, L G, will now build up a new kind of yolk, L(A+,a)B C 

 . . . . X Y Z. In development, this yolk will no more form the 

 previous tissue L A, but the new one L(A+ a) — i.e., the acquired 

 character ( + a) — has become hereditary. 



( Read, July 6, 191 7.) 



Horse Chestnuts for Munitions. — The services 



of children are now being utilised in Great Britain for the col- 

 lection of horse chestnuts intended to be used in the preparation 

 of munitions. According to present indications, the Ministry 

 of Munitions will receive at least 25,000 tons of nuts, repre- 

 senting about one-eighth of the country's total crop for the 

 season. Every ton of nuts thus gathered means the saving of 

 half a ton of grain. 



