EMBRYO, SEED AND CARPEL IN THE DATE. 141 



befo 



germination. Of much information regarding the latter 



from 



combe and i 

 and others. 



marked mechanical 



justment of the embryo and endosperm. At first the embryo 

 is spherical in form (f. 14) becoming, at 13 weeks (f. 16) 

 broadly ovate-conical, with the base against the micropyle. 

 Scarcely any change in shape is now to be noted for two 

 weeks, after which, however, the growth is rapid. Within 

 another month, the definitive form and almost full size are 

 attained, (f.18). This, especially, is the period of mechan- 

 ical adjustment, for it is now that the endosperm is also 

 growing rapidly, and that the secondary thickening of the 



form the reserve 



But 



th 



endosperm is relatively much more 



em 



;e the cotyledonary end of the embryo, which 

 is at length nearly obliterated (f. 15-19) . For the purpose of 

 enabling the reader to follow the changes which ensue dur- 

 ing this period, I have chosen six stages of development, 

 and represented these in figures 14a-19, inclusive, to which 

 the following descriptive notes may be applied. 



•Zone a. Cells show no disintegration, but are large, 



rm 



in 



Figure 14a. 



with a relatively small amount of protoplasm, and reduced on content. 

 No blue reaction in the cell- walls with iodine.— Zone a becomes dif- 

 ferentiated into zones a and a'.— Zone 6. Small endosperm cells with 

 divisions taking place approximately parallel to the integument. 

 This characterizes also the peripheral endosperm, beneath the inner 

 integument. — Zone 6'. 



zone 6. 



Figure 15.— Zone a. Cells with collapsed walls, empty or with 



minute protoplasmic content and a droplet of oil. The walla react blue 



to iodine. In the space between a and the embryo, oil accumulates. 



Zone a' . Uncollapsed cells within the digestion zone. The outermost 



show no change. The innermost show a more or less disintegrated 





