422 TorRREY : CYTOLOGICAL CHANGES 
indebtedness to Professor Francis E. Lloyd for the suggestion of 
the research and kindly criticism during its progress. 
Methods.—The seeds were soaked over night in water to 
soften the coats, and were then placed between layers of filter 
paper in a moist chamber. The embryos at different stages of 
growth were cut from the grain together with that part of the 
endosperm in immediate contact with the scutellum. The first 
series was made at time intervals. The embryos were fixed ap- 
proximately every 12 hours for two days, and then at 24-hour 
intervals. This was found to be unsatisfactory as the rate of 
growth in different seeds varied greatly, and thus the chances of 
obtaining a sequence of stages was lessened. Accordingly, 4 
series from the beginning of germination to five days was secured 
with the rate of growth as a guide, and without reference to time 
intervals. The length of the radicle and plumule served as an 
indicator. The best fixation was effected by the use of sublimate 
acetic 2 per cent., or of alcoholic acetic (70 per cent. alcohol 2 
parts and glacial acetic acid 1 part). Flemming’s fluid caused ex- 
cessive blackening. Iron haematoxylin proved to be by far the 
most satisfactory stain, either alone or followed by Congo red as 4 
counter stain. Auerbach’s method, also, was of some value. The 
sections were cut for the most part 5 » in thickness. 
I. Description oF SEED. (PL. 20, F. !) 
Without entering upon a description of the various seed coats, 
a kernel of corn may be said to consist of two distinct elements— 
the endosperm and the embryo. The former occupies the larger 
part of the seed and partly clothes the adjacent embryo. The 
latter is on the furrowed flattened side of the kernel. It ® 
thickest at the end attached to the cob, and gradually slopes to # 
point reached at about four fifths the length of the grain. Between 
the axis of the plantlet and the endosperm there is a thickened 
shield-like expansion of the hypocotyl, supposed by many to be 
the homologue of the cotyledon, and known as the scutellum- 
This is the special organ of absorption, The endosperm consists 
of large cells filled with starch grains imbedded in a mane 
proteid matter. Several layers of crushed and empty cells SP 
arate these well-filled cells from the scutellum. As these cells 
