History of Wheat. 



however, correlated with anatomical differences in the structure of 

 the shell or pericarp of the grain, which still more accentuate the 

 separation of the wheats proper and the Spelt wheats. From this 

 standpoint the Polish wheat, which generally is treated as a dis- 

 tinct species, has to go with the wheats proper. Those are the 

 principal kinds as they present themselves to the practical man 

 without consideration of their taxonomic value. At present they 

 are rather definite and distinguishable units, whatever their place 

 and relative position in the evolution of the wheats may be. It 

 need only be added that the various Spelt wheats differ more 

 from each other than do the wheats proper. Those ten wheats, 

 however, are not only fairly well definable, but they are also 

 constant in the sense that we cannot turn Soft wheat into Hard 

 wheat, or Spelt into Emmer; nor has it been proved so far that 

 the two wild wheats can be transformed into their assumed culti- 

 vated representatives, as we can, for instance, convert the wild 

 carrot into the garden carrot. But too much stress must not be 

 laid upon that, as Triticum cegilopioides, the assumed primitive 

 form of the Einkorn, has not been much experimented with, whilst 

 Triticum dicoccoides, the supposed Emmer, was only rediscovered 

 quite recently — having been known before solely from a single 

 herbarium specimen — and is approaching now only its second 

 harvest in the experimental grounds at Poppelsdorf, Bonn. In 

 valuing the affinities of those wheats and tracing their descent, we 

 have therefore to rely on the varying degrees of their structural 

 resemblances, the nature of the differentiating characters, the 

 presence or absence of intermediate forms, other than hybrids, 

 and on analogies. We have seen that the wheats are divided into 

 two groups by what is no doubt a practical difference of the 

 highest order; the looseness or tightness of the grain in the husks, 

 combined with the toughness or brittleness of the spindle, on the 

 one hand, and the thicker or thinner grain shell, on the other. 

 These are three characters, each by itself, as characters in grasses 

 go, apparently of considerable taxonomic value ; but if we con- 

 sider their part in the economy of those plants and the constancy 

 with which they occur side by side, it becomes clear that they are 

 really very closely correlated and behave functionally like one 

 character. Among the wild grasses effective dissemination is pro- 

 vided for by a great variety of contrivances and generally regu- 

 lated so that the grains are dispersed singly or nearly so, and at 

 the same time protected by some covering until germination sets 

 in. In the two wild wheats this is secured by the breaking up of 

 the spindles on maturity, releasing thereby the individual one- or 

 two-grained spikelets and by the permanent enclosure of the grains 

 in the husks. We find the same conditions in the grasses which are 

 generally admitted as the primitive forms of rye and barley. In cul- 



