44 THE POPULAR SCIENCE MONTHLY 



we should have a larger number of categories of types; now, of these 

 types there would be eight categories which would be constant. These 

 would be ABC, A B c, A~b C, aB C, Ah c, aB c, ab C, ale; two of 

 these types repeat the primitive parents, the others are new. If these 

 latter are not allowed to fertilize each other or to be ferilized by other 

 forms, but are self-fertilized, they will be constant in their descendance, 

 which will behave like a new stable species. 



From this we see that the mosaics of gens, which constitute the 

 hereditary capital of species and varieties, are dissociable and that the 

 gens, in the phenomena preceding or accompanying fecundation, 

 execute a sort of chasse-croise, the final result of which is determined 

 by the laws of probability. 



The number of types and new forms increases rapidly with the 

 number of antagonistic characters. For 2 antagonistic gens there will 

 be 4 types; for 3 gens, 8 types; for 4 gens, 16 types; for 5 gens, 32 

 types; for 6 gens, 64 types; for 7 gens, 128 types — and these types are 

 constant from the second generation (in which they appeared) on. 



Here we have infinite perspectives which appear on our new scien- 

 tific horizon. 



But to obtain these remarkable results with the desired mathe- 

 matical certainty we must start with biological unity, with a pure line, 

 with a single grain of wheat, the parent of a whole line similar to it. 

 From this we see the importance of Aaronsohn's discovery; it will 

 allow us to do methodically in a few years all that 6,000 years of culti- 

 vation and unconscious selection have gained for us and perhaps also 

 to combine and associate characters which escaped the intuitive observa- 

 tions of primitive peoples. 



For example, we can associate the hardiness of the wild wheat with 

 the vigor of growth of a cultivated wheat, the rust resistance of a wild 

 variety with the seed quality of a cultivated variety, etc. 3 



But wheat is not for agriculture, wheat is to make bread. This 

 making of bread is almost as old as the cultivation of wheat, and yet 

 the conditions of fermentation necessary to raise the dough under the 

 influence of leaven are still insufficiently known. We know that in 

 this sour dough, the natural leaven, there are lactic bacteria which 

 secrete an acid and give off a gas as well as alcohol. By means of this 

 fermentation the dough, permeated by the gas which raises it, gives a 

 lighter, more digestible bread. We are far from knowing all of the 

 details of the process of bread fermentation. However that may be, 

 for ages beer yeast has been introduced into the leaven, or, as in the 

 time of the Eomans, the "must of fermenting wine." These yeasts 



3 Bateson, ' < Mendelism, " Cambridge, 1909. See "Mendelism," Punnet, E. 

 C, ed. 7, Cambridge, 1909, p. 58. 



