Nov., 1903.] The Development of Corn. 3 



THE DEVELOPMENT OF THE SPIKELET AND 

 GRAIN OF CORN.'^ 



C. C. POINDEXTER. 



With a view to a later study of the subject of xenia in corn, a 

 preHminary observation of the development of the carpel and 

 endosperm was attempted in order to see what relation exists 

 between them, since some of the authorities mentioned claim that 

 the effect of double fertilization is shown in the carpel wall, while 

 others assert that it is shown only in the endosperm and embryo- 

 sac. The embrj^ology of the corn grain also was studied and 

 figures were made of the ovule at different stages beginning with 

 the archesporial cell and ending with the fully developed embryo. 

 These drawings and observations not being complete will be 

 reserved for another paper. As there are few recent descriptions 

 and figures of the develor ment of the spikelet and grain, it was 

 thought advisable to publish this general part at the present time. 



The writer wishes to acknowledge his indebtedness to Professor 

 John H. Schaffner for invaluable suggestions and criticisms in the 

 preparation of the paper. 



The material used was common white field corn gathered at 

 different stages of maturity from the corn field of the Ohio State 

 Universit}- in the summer of 1902. The very 3-oung ears were 

 left whole or cut in two, while the larger were quartered length- 

 wise and, after killing, cut into pieces convenient for use. The 

 material was killed in chrom -acetic acid and preserved in 70 per 

 cent alcohol and later imbedded in parafiin. Pieces of the younger 

 ears were cut from three to six grains in length, while single 

 grains were used of the older stages. The sections were cut 

 12-18 /A in thickness, and stained on the slide in anilin-safranni 

 and gentian-violet and iron-alum-haematoxylin. All things con- 

 sidered, corn is an easy object to work with, but in using the older 

 grains precaution should be taken to guard against shrinkage of 

 the endosperm tissue. This may be practically obviated by punc- 

 turing the grain with a dissecting needle before killing. The 

 outer covering of these grains may also be sliced off on either side 

 to permit of rapid penetration. The iron-alum-haematoxalyn 

 proved to be the most efficient stain and was soon the only one 

 used. 



The production and development of new varieties of plants 

 depends upon the fact that the offspring of a cross par- 

 takes of the characters of both parents, which, according to Men- 

 del (i) follows a definite law of proportion in some species. 

 Some plants appear to be more susceptible to hybridizing than 



••■ Coutributions from the Botanical Laboratory of Ohio State University. XIV. 



