164 



Journal of Agricultural Research voi. xviii, No. 3 



occasional vacuole in the former. It is stated that large starch granules 

 and largeornumerous vacuoles are associated in starchy kernels, and that — ■ 



the difference in structure between the homy and the yellow kernels is also accom- 

 panied by a difference in composition, the yellow kernels containing less nitrogen. 



The size of the starch granules in yellow-berry and in hard, flinty 

 wheat was studied by the writer. Yellow-berry kernels were taken from 

 a number of pure wheats, and samples of the opaque or yellow portions 

 of the endosperm were removed from these by means of a dental drill. 

 Samples were taken from 10 kernels to get a fair average. Similar sam- 

 ples were taken from the horny or flinty portion of the same 10 ker- 

 nels, the drill being burned off each time after use. 



The yellow-berry endosperm samples were shaken up in alcohol, 

 stained with iodin in potassium iodid, and mounted for measurement 

 with a Bausch and Lomb filar micrometer. Five hundred measure- 

 ments were made for each lo-grain sample of each strain of wheat used. 

 In all cases, the largest starch granules visible in any given field were 

 the ones chosen for measurement. The results of this study are given 

 in Table IV. 



Table IV. — Measurements of starch grains from yellow-berry and from, hard kernels of 



10 pure lines of wheat 



Sample No. 



Measurement of starch granules 

 in — 



Hard grains. 



Soft grains. 



Difference 



between soft 



and hard grains. 



951 



1094 



III9 



II26 



II50 



151^8 



1592-6 



1687-4 



1687-8 



1687-10 



Average 



Mm. 

 o. 030726 

 . 024999 

 . 025910 

 •027315 



• 032587 

 .027873 

 . 028234 



• 029413 

 . 031869 



• 033200 

 . 029212 



Mm. 

 o. 024819 



• 029095 

 . 023940 



• 024977 

 . 027981 

 . 028878 

 . 028969 

 ■ 027965 

 . 023822 

 . 028519 

 . 026897 



Mm. 



— O. 005907 

 -|- . 004096 



— . 001970 



— .002338 



— . 004606 

 -|- . 001005 

 -1- .000735 



— . 001448 



— . 008047 



— . 004681 

 . 002315 



These results show that in 7 out of 10 cases the average diameter of 

 the starch grains in the hard portions of the kernels was greater than 

 in the soft or yellow-berry portions, while in 3 cases it was less. 

 These results are exactly the reverse of those obtained by Lyon and 

 Keyser (5, p. 23-26). 



The writer is unable to account for the discrepancy in the two sets of 

 data. It would seem, however, that since in the present case an average 

 of 500 measurements was taken and the largest starch grains in each 



