126 STUDY OP COMMON PLANTS. 



take the place of antheridia. A fully formed archegonium 

 is a flask-shaped body with an elongated neck, and an 

 enlarged ventral portion, within which is the oosphere. 



Fertilization takes place by the mingling of the sub- 

 stance of an antherozoid with that of the oosphere, after 

 the antherozoid has forced its way down through the long 

 canal of the neck. The fertilized oosphere, now called the 

 oospore, becomes septate, and by still further cell-division 

 and growth the capsule with its seta, spores, and various 

 parts already described, is formed. 



With suitable material and sufficient time the student 

 can readily verify most of the facts here given. 



The peat mosses, Sphagnacese, are easily obtained in 

 many parts of the country, and afford an opportunity for 

 extended and profitable comparative study. Their habits, 

 structure of the vegetative organs, and fructification, all 

 present interesting points of difference from the true 

 mosses. 



LIVERWORTS. Hepaticce. 



The liverworts are closely allied to the mosses, their 

 cycle of development being essentially identical with that 

 of the latter group. Accordingly our work will be re- 

 stricted to a comparison of the general characters of some 

 of the most easily procurable liverworts. Representatives 

 of the genera named at the beginning of this section are 

 widely distributed and easily obtained through a consid- 

 erable part of the year. Lunularia is of almost universal 

 occurrence in greenhouses, and while seldom if ever found 

 in fruit, almost always has gemmae in different stages of 

 development. Conocephalus is common and abundant in 

 moist, shady places. The floating species of Riccia have 

 a wide range, as do also some of the species of Porella. 



