90 TEXTBOOK OF BOTANY 



plant ; sometimes they may be carried by insects. In some way, 

 at any rate, antherozoids reach the female head ; and, swimming 

 about here, some of them come into the neighborhood of an archegone 

 and immediately swim to the opening of the neck. They do this 

 because a substance is given ofE from the archegone which serves as 

 a stimulus to the antherozoids ; they swim toward the point from 

 which the stimulating substance comes, and many antherozoids thus 

 attracted may swarm about the mouth of the archegone. Some of 

 them enter it and swim down the canal, through the liquid which 

 fiUs it, and finally one antherozoid unites with the egg. Since this 

 union of antherozoid and egg occurs inside the archegone, 'from which 

 the egg (and the zygote as well) cannot escape, it follows that the new 

 plant which is to grow from the zygote must begin to develop within 

 the archegone. 



119. Germination of the Zygote. — Germination occurs 

 very soon after fertilization. As a result of the growth of 

 the zygote and of a series of cell divisions, a long, slender 

 embryo is formed. The lower end of the embryo grows down 

 through the base of the archegone into the tissues of the stem 

 of the parent plant. The growth of the new plant inside the 

 archegone seems to stimulate some of the cells of the latter 

 to renewed growth and division, and for a time the lower part 

 of the archegone grows rapidly enough to keep pace with the 

 development of the embryo. But after a time the growth 

 of the embryo becomes more rapid than that of the arche- 

 gone ; the latter is now broken, and the greater part of it is 

 carried up on the top of the embryo (Fig. 46, A). This cap, 

 formed from the archegone, remains for a time, but sooner 

 or later it falls off. The lower end of the embryo remains 

 imbedded in the tissues of the parent plant. 



120. The Spore-bearmg Plant (Fig. 43, A, b).~As the 

 new plant continues to grow, its upper portion becomes 

 thicker and develops into a spore sac ; this is supported on a 

 long, slender stalk. It is by means of the lower end of the 

 stalk, which is imbedded in the tissues of the parent plant, 

 that the new plant absorbs water and other food substances 

 from the parent. The upper end of the stalk, where it is 



