New YorK AGRICULTURAL EXPERIMENT STATION. ato 
sumably to differences in composition of the grain, though the 
writer has not figures at hand to support this statement. Soule 
and Vanatter? have recently demonstrated the influence of cli- 
mate on protein content of wheat, also the influence of fertilizers 
on the same element. Snyder* has also recently called attention 
to the great differences in protein content that obtain in different 
varieties of wheat and among different samples of the same 
variety. Prof. Snyder did not touch on the subject of specific 
gravity directly, though his investigations are such that his 
results may to some extent be brought into relation with the work 
here reported. He showed, for instance, that light colored wheat 
is lower in protein content than dark colored wheat from the 
same sample. As already indicated in this report, the light 
colored kernels are lower in specific gravity than the dark colored 
ones. We have, then, here a correlation between the specific 
gravity of the seed and its chemical composition. Prof. Snyder 
_also pointed out the physical basis for these differences in color 
and showed them to be due to differences in gluten content. 
In the case also of the field corn commonly grown in New 
York State, as has already been stated in this report, the specific 
gravity is low and the protein content is also well known to be 
low. But the field corn high in protein content now being grown 
in the west is relatively high in specific gravity. 
These are, however, only particular and isolated cases and do 
not establish the principle that differences in specific gravity are 
correlated with differences in composition. The subject of the 
relation of specific gravity to chemical composition has been 
investigated by a number of workers but, so far as has come to 
the writer’s attention, uniformly with the conclusion that the 
one is not a reliable index to the other. This is for the reason 
that there are so many extraneous factors entering in which are 
liable to obscure relations. A conclusion of this kind was 
reached by Wollny, who remarks that in many cases the specific 
gravity of the seed is an index to its composition, but that there 
are so many exceptions that in practice no general rule can be 
laid down. Marek, Wolffenstein and others have reached similar 
conclusions. 
2 Bul. Tenn. Agr. Expt. Sta., Vol. XVI, No. 4. 
3 Minn. Agr. Exp. Sta., Bul. No. 85. 
