SUMMER MEETING. 



45 



*>* 3b CO ATS. 



WHEAT 



COAT. 



KA KNIEVEl S 



Fig. 19 



The fifth and sixth coats are much 

 alike, light colored and transparent, 

 and very thin. Within and next to the 

 sixth coat are the large cells which con- 

 tain the gluten, and still within the 

 gluten cells are those containing starch. 

 Along the groove or furrow is a fibro- 

 vascular bundle containing spiral ves 

 sels and fibres. In the third coat are 

 found many irregular canals which run 

 into each other. 



At the apex of the kernel are many 

 hairs, each consisting of one cell. 

 Figures IS and 19 will help to explain the meaning of my descriptions. 

 Dr. Beal : Flowers produce more or less pollen, which is the fertilizing ele- 

 ment. Our apples, or peaches, or pears, or strawberries not unfrequently fail 

 to set fruit because the pollen is not well developed or does not get to the stigma 

 of the pistil where it can fertilize the ovules. 



The structure of a grain of pollen, and the way in which it grows down the 

 style is a difficult one to investigate, and has not received much attention from 

 the botanists of America. I call on one who has made some successful 

 observations and experiments, my daughter, 



Jessie I. Beal: Pollen grains are formed in the upper part of the stamens, 

 called anthers. The grains have a thick, brittle outside coat, the extine, and 

 an inner coat which is quite thin, 

 called entire. The grains of pollen 

 are usually nearly or quite spherical, 

 and are filled with protoplasm. Two 

 parts of the protoplasm are usually 

 found as bodies more or less distinct. 

 These are called nuclei. The outer 

 covering of the pollen is often marked 

 in some way with spines or ridges, but 

 it is often smooth. One of the nuclei 

 is long, and is called the germinative 

 nucleus, while the other is nearly spher- 

 ical, and is called the vegetative 

 nucleus. 



When the pollen falls on the stigma of a plant of the same species, it begins 

 to germinate, in most cases, in a few hours. 



It sends out a tube through the bursted outer coat, and grows down the style 

 until it reaches the ovule in the ovary. In most pollen grains the tube starts 

 from any point on the grain, but sometimes they project from a certain 



o 



Fig. 20. 



