REPEODUCTION OF ACROGENS. 



769 



ture, which then becomes fertilized. No free spore is, however, 

 produced, but the nucule drops off, and after a certain period 

 germinates in a manner closely resembling the seed of a mono- 

 cotyledonous plant, by which a new plant is at once formed 

 without any intermediate pro-thallus being produced. 



2. HepaticacecB or Liverworts. — The reproductive organs of 

 this order closely resemble those of Mosses. They are termed 

 Antheridia {figs. 811 and 812) and Archegonia or Fistillidia 

 {figs. 813 and 814), the former representing the male sex, and the 

 latter the female. "When the antheridium bursts {fig. 812), it 

 discharges a number of small cells, which also burst, and each 

 emits a very small 2-ciliated spiral spermatozoid. These sper- 

 matozoids are supposed to pass down the canal of the archego- 

 nium {fig. 814) to the germ or embryonal cell which is situated 

 at its bottom, which thus becomes fertilized. This cell after 

 fertilization undergoes various important changes, as already 

 noticed (see p. 371), and 



ultimately becomes a spo- Fig. 1110. 



rangixim enclosing spores. 

 When these spores germin- 

 ate, they generally produce 

 a sort of confervoid struc- 

 ture or mycelium {prothal- 

 lium), which in its after 

 development resembles the 

 like structure of Mosses 

 {fig. 1110). 



3. Musci or Mosses. — The 

 reproductive organs of this 

 order consist of antheridia 

 {fig. 802) and archegonia 

 {fig. 803), which closely re- 

 semble the same structures 

 in the Hepaticacese. Ferti- 

 lization takes place in a 

 similar manner (see above), 

 and the changes which take Fig. mo. ProthalUum or protonema of a 

 piace atter lertliization m ^^^^ protonema ; «, Bud ; b. Young leafy 

 the embryonal cell which stem ; r. Rootlets. 



ultimately forms a sporan- 

 gium containing spores {fig. 810) have been already described. 

 (See p. 367.) 



In germination, the spores at first form a green cellular 

 branched mass or iDrothallitim, resembling a Conferva, which is 

 sometimes termed Xhe protonema (see p. 369). Upon the threads 

 of this structure {fig. 1110), buds (a) are ultimately produced, 

 which grow up into leafy stems {b), upon which the archegonia 

 and pistillidia are afterwards developed. 



3d 



