
76 STORRS AGRICULTURAL EXPERIMENT STATION. 
which asparagin may be taken as the type. ‘he data con- 
cerning the proportions of these different nitrogenous com- 
pounds are few, but it appears from the work of ‘Teller?, 
Snyder’, Wiley*®, and others that not less than 96 per cent. of 
the nitrogen of the seeds of cereals (and probably the legumes ) 
may be assumed as present in proteid combinations, and not 
over 4 per cent. in non-proteid combinations. 
While the proportion of non-proteids in animal foods and in 
the cereal grains and their manufactured products is relatively 
small, the quantity in vegetables and fruits is at times large, 
so that in some cases as much as two-thirds of the total nitro- 
gen may occur in non-proteid forms. ‘The methods of separa- 
tion are too unsatisfactory and the amount of data too small 
and conflicting to enable us to estimate the exact proportion of 
proteid and non-proteid nitrogen in the different vegetables 
and fruits. From the best information available we are led to 
the rough estimate that, in round numbers, 60 per cent. of the 
nitrogen in vegetables such as potatoes, turnips, cabbage, let- 
tuce and the like, and 70 per cent. of that in fruits occurs in 
proteid combinations. 
The nitrogen factor of proten.—It has already been pointed out 
that the portion of nitrogen in protein compounds varies consid- 
erably. It has for a considerable time been the general custom 
to assume an average of 16 per cent. of nitrogen in protein, 
including both proteids and non-proteids. In other words the 
total nitrogen has been multiplied by the factor 6.25 to obtain 
the amount of protein in the given material. ‘The proteids of 
muscular tissue, such as are found in ordinary meats, appear to 
contain, in general, about 16 per cent. and the non-proteids of 
such tissue a somewhat larger proportion of nitrogen. How- 
ever, neither the amount of’ these non-proteids nor their pro- 
portion of nitrogen seems to be sufficient to cause any large 
error in the use of the factor 6.25 for estimating the total pro- 
tein.* In the flesh of some kinds of fish, as the cod and more 
especially the skate, the total nitrogenous material seems to 
1, Arkansas Exp. Sta., Bul. No. 42, p. 100. 
2. Minn. Exp. Sta., Bul. No. 63, p. 528. 
3. U.S. Dept. Agr., Division of Chemistry, Bul. 13, Part IX., p. 1247. 

* This view is confirmed by the results (unpublished) of recent investigations by 
Prof. Grindley, Univ. of Illinois, in cooperation with the U.S. Dept. Agr. 
