29 



In the British Islands 600 urn mosses and 200 liverworts, or 

 scale mosses, are now enumerated, belonging to numerous genera. 

 Many of them have a wide distribution in the temperate zone, 

 for a great many of the North American and temperate Europe- 

 an mosses are found to be identical with those of the British 

 Islands, and even in the Southern Hemisphere, in New Zealand, 

 some of the British mosses are found to grow. 



Wilson's " Bryologia Britannica," published In 1855, is one 

 of the best works on these plants. It is now a scarce book, as 

 many copies of the edition were destroyed by fire in the pub- 

 lisher's office. 



Hobkirk's sj'nopsis of the " British Mosses," second edition, 

 published in 1884, is a handy book, and gives a short description 

 of all then known. Jameson's Illustrated Guide to British 

 Mosses, 1893, contains an analysis of all the British species. A 

 very comprehensive work on them is now in course of issue. 

 Dr. R. Braithwaite's " British Moss Flora," has beautiful fig- 

 ures and magnified sectional drawings from nature of all the 

 species, which are most essential for students of these plants. 



The life history of the Muscineae shows a regular and well- 

 marked alternation of generations. The germinating spore does 

 not at once give rise to what is known as the moss-plant, but 

 produces an embryonic body, called the protonema, which con- 

 sists generally of a branched filament, but occasionally of a fiat 

 layer of cells. The protonema is mostly inconspicuous and 

 short-lived in the Hepaticae, whilst in the mosses it is more 

 amply developed, and sometimes persists from year to year. 



The moss-plant is the adult sexual form, and on the adult 

 shoot are produced the sexual organs, Antheridia and Arche- 

 gonia. These organs are borne sometimes both on the same 

 plant ; in other cases the Antheridia and Archegonia grow on 

 separate distinct plants when it is dioicous, although both forms 

 grow from the same protonema. 



Group 3, — Pteridophyta (Vascular-Cryptogams). — This in- 

 cludes the FilicincB, or Ferns ; Equisetincs, or Horsetails ; and 

 Lycopodince, or Club-mosses. The life history in this group pre- 

 sents a well-marked alternation of generations. The spore- 

 producing form in the Ferns is the more conspicuous, constitut- 

 ing the well-known Fern-plant. 



