100 MOSS. 



sexual character was fully established. It was also in 

 mosses and liverworts that the antherozoids were first 

 detected, being seen by SchmideP in 1762, but without 

 detecting their cilia, which were discovered by Unger 7 

 in 1837. 



After fertilization has occurred the oosphere clothes 

 itself with a cell wall, and grows at once into a fruit, as 

 in Marchantia. This fruit is in many ways remarkable, 

 as will be more apparent in some respects after study- 

 ing the ferns and club-mosses. It will be remembered 

 that in the plants already studied, with the exception 

 of Marchantia, the sexually formed spore produced a 

 plant like the parent, after a longer or shorter period of 

 rest. In Atrichum, however, it grows, not into a plant 

 like the parent, but into a highly complicated structure, 

 the fruit or sporogonium, which in its turn forms 

 asexual spores that produce plants like the original. 

 This process, known as an alternation of generations, 8 

 is less strongly marked in liverworts, and reaches 

 its height in ferns. 



The base of the seta which is thrust into the apex of 

 the leafy plant, has no organic connection with it, and 

 while in Atrichum it pulls out with some difficulty, in 

 many mosses it comes away easily without preparatory 

 treatment. This feature further emphasizes the dis- 

 tinctness of the so-called fruit and the parent plant, 

 from which in quite a parasitic fashion it derives its 

 nourishment. 



6 Icones plantaram, p. 85. 



7 Nova Acta A. C. L.-C. Nat. Cur., xviii, p. 791. 



8 Sachs, Text-book, 2nd Eng. ed. , pp. 226,954; Vines, Journal of 

 Botany, 1879 ; Underwood, Our native ferns and their allies, p. 35. 



