10 



A TERN BOOK JTOE EVERYBODY. 



vej an erroneous notion. There is no alternative , then, 

 but to call it a " prothallus," and, if the writer and the 

 reader equally agree as to the meaning of the word, it will 

 be just as easy to use the right one, as to coin one for the 

 purpose. But, to return to this curious filmy "prothallus." 

 When mature, two kind of organs are produced from its 

 under surface, and these represent the male and female 

 principle in the process of fertilization. One kind of 

 organ contains the germ of the future plant, a kind of 

 bud in its most rudimentary state : this we may term the 

 germ-cell. The other organs represent the fertilizing 

 principle, and may rudely be designated little bags or 

 cells containing active little thread-like bodies {spermato- 

 zoids) which, when they are liberated from the cells which 

 contained them, move about as though endowed with 



Fig. G. 



animal life. (Pig. G.) "When the little bud or germ has 

 reached a proper state of maturity, it protrudes from its 

 cell and comes into contact with some of these mysterious 

 little active thread-like bodies, and thus the bud is fertil- 

 ized. Gradually the lively bodies become still and dis- 

 appear, the bud increases in size, the green membrane, 

 which is called the prothallus, disappears also, and nothing 

 is left but the young bud, which begins to put on the 

 appearance of a miniature fern plant, developes little 

 leaves, and grows up in the likeness of the parent plant, 

 from whence the spores or seeds were first taken. 



This is merely a rough outline of the process which 

 takes place in the growth of a young fern from spores. 

 The terms which we have been compelled to use, in order 



