15 



it ia sometimes Bupplemented by appendages to the nerve as in 

 Polytrichum, the nerve of which is thickly studded with lamellae 

 which are rich in chlorophyll and must enormously increase the 

 assimilative power of the leaf. The mosses of this genus form an 

 tilmost woody stem, so stiff that they are sometimes used for mak- 

 ing brooms, so that the quantity of material assimilated, as com- 

 pared with other mosses, must be very great. 



The leafy moss of the first generation eventually bears the 

 sexual organs, which are known as antheridia and archegonia. 

 These are best observed in those mosses, such as Funaria, many 

 species of Bryum, &c., in which they are produced on separate 

 plants, when the moss is said to be dioecious. The antheridia are 

 to be found in small rosettes generally of a yellowish colour and 

 surrounded by modified leaves called the perigonial leaves. They 

 consist of oblong sausage shaped bodies and are surrounded by 

 curious filaments known as paraphyses, the functions of which are 

 unknown, though they probably in some way regulate the 

 evaporation of water which plays so important a part in the life of 

 a moss. The antheridia when mature open at the apex and the 

 antherozoids or male fertilizing elements escape. These can only 

 live in water in which they swim about by means of a cilia. Their 

 movements may be readily observed by examining a ripe 

 antheridium in water under the microscope. 



The archegonia or female flowers are flask-shaped bodies some 

 what similar in shape to the pistils of phanerogams. Like the 

 antheridia they are surrounded by modified leaves, known in this 

 case as the pericheetial leaves, and they have paraphyses growing 

 with them. The upper part of an archegonium consists of a 

 hollow neck down which the antherozoid travels to fertilize the 

 oosphere. The first generation of the moss is completed on the 

 fertilization of the oosphere which now starts on a new career of 

 its own. It grows slowly, downwards into the substance of the 

 moss-stem at the expense of which it is nourished, and upwards 

 when it shortly ruptures the swollen archegonium, the upper 

 part of which is borne on its growing point and forms the 

 calyptra. This is often a very beautiful object and under its pro- 

 tection of the growing point soon develops into the more or less 

 cylindrical capsule. In the more highly organized mosses the 

 capsule dehisces by means of a lid to permit of the escape of the 

 spores, which are formed round the central axis or columella of 

 the capsule by free cell division, with the intervention of a 

 mother-cell, in the same way as the pollen grains of the flowering 

 plants. The most beautiful part of the capsule is perhaps the 

 peristome, which becomes visible on the fall of the lid and sur- 



