752 PHYSIOLOGY. 



plants in all the orders of this sub-division of the Cryptogamiaj 

 there can be no doubt, although the actual process of fecun- 

 dation has only been clearly observed in the Fihces, The 

 sexual organs in all are also of an analogous character, and are 

 of two kinds, one of which is termed an antheridium, which 

 contains spirally wound ciliated spermatozoids, and which is 

 regarded as the male organ ; and the other, called an archego- 

 nium or pistillidium, in which an embryonal cell or germ-cell is 

 contained, which appears to be the female organ. Fecundation 

 is supposed to take place by the contact of a spermatozoid with 

 an embryonal cell or germ-cell. In the Characeae no distinct 

 archegonium occurs, but the nucule is considered as the repre- 

 sentative of that structure. We have already described the struc- 

 ture of the reproductive organs of Acrogens (pp. 368—382), both 

 before and after fecundation ; it will be only necessary therefore, 

 in the present place, to say a few words upon the mode in which 

 fecundation is supposed to take place in the different natural 

 orders included in this division of the Cryptogamia. 



1. CharacecE or Charas. — In this order we have two kinds of 

 reproductive organs, called respectively, the globule {fig. 813, gr), 

 and the nucule {fig. 813, n) ; the former is regarded as the 

 viale ; and the latter as the female. Fecundation is believed to 

 take place, by the passage of the spermatozoids of the globule 

 {fig. 814) down the canal which extends from the apex of the 

 nucule {figs. 816 and 817) to the central cell of the same struc- 

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

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

 period germinates in a manner closely resembling the seed of a 

 monocotyledonous plant, by which anew 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. 808 and 809) and Archegonia or ristillidia 

 {figs. 810 and 811), tlie former representing the male sex, and the 

 latter the female. When the antheridium bursts {fig. 809), 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. 811) to the germ or embryonal cell which is situated 

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

 fertilization imdcrgoes various important changes, as already 

 noticed (see p. 380), and ultimately becomes a sporangium 

 enclosing spores. When these spores germinate, they generally 

 produce a sortof confervoid structure or mycelium {pro-thallus), 

 which in its after development resembles the like structure of 

 Mosses {fig. 11 02). 



3. Musci or Musses.— The reproductive organs of this order 

 consist of antheridia {fig. 799) and archegonia {fig. 800), which 



