the Grain of Wheat ( Triticum vulgar e). 119 
sections were carefully kept in series, and were taken at short intervals, each 
grain furnishing about fifteen sections. Delafield’s haematoxylin was used 
as a single stain in this case, in greater concentration with a shorter 
immersion. 
Three problems presented themselves for consideration with regard to 
the material so prepared : — 
(1) Are any cytological differences, which might affect the strength, to 
be observed in the developing grains of ‘strong’ (Red Fife) and ‘weak 
(Square Head’s Master) wheat when grown in the same locality, and there- 
fore subjected to similar climatic conditions ? 
(2) Are there any cytological differences, indicative of strength, to be 
found in the developing grains of one variety of wheat (Square Head’s 
Master) when grown in the same field, on similar soil and under the same 
climatic conditions, but subject to radical differences in manuring? 
(3) Is the reputed difference in strength between grains of the same 
variety cut ‘ green ’ and ‘ dead ripe ’ due to cytological changes as ripening 
proceeds ? 
Considering these three points separately : — 
(1) It has been suggested ( 3 ) that varying strength is partly or entirely 
due to different climatic conditions, but bakehouse experiments have shown 
that this statement is much too general, as, other things being equal, some 
strong wheats, e. g. Red Fife, remain strong whatever the climate in which 
they grow, and vice versa. The Red Fife wheat under consideration had been 
spring sown, and therefore, date for date, was not at such an advanced stage 
as the autumn-sown Square Head’s Master — in fact, while the Broadbalk 
wheat was cut on August 5, the Red Fife was left standing till August 15. 
In comparing the two varieties, due allowance had to be made for this 
difference in the age of the grain. It was found that the nuclei undergo 
considerable changes during the progress of ripening of the grain. In the 
earlier stages they are quite normal and perfect, well formed, and possessing 
nucleoli. As the grain grows older changes take place, which will be 
more fully described later under the head of endosperm development, till 
finally, by the time the grains are matured, the nuclei are very much dis- 
organized in structure, particularly in the deeper-seated cells furthest away 
from the aleurone layer. The nuclei of the aleurone layer do not undergo 
this disorganization, and the cell contents seem to remain unchanged when 
once they are fully organized. The cells of the starchy endosperm which 
lie nearest to the aleurone layer were found to contain rather more protein 
than the rest, as was shown by the Xantho-protein reaction. Freshly cut 
hand-sections were placed in strong nitric acid, and left for a minute or two 
till they were quite transparent ; after washing in water they were trans- 
ferred to ammonia and left for a few minutes. After a final washing in water, 
the sections were at once examined under the microscope, when the cells 
