President's Address. 185 



but they liave never been transformed into leaves, nor are 

 they arranged spirally round the axis. It has also been 

 suggested that the capsule consists of modified leaves ; but 

 the fact of stomata occurring on it when they never occur 

 on the leaves, disproves the theory. These stomata are 

 easily seen on the points of PolyhHchum and Funaria. 



The peristomes are formed by cell thickenings, the outer 

 peristome being composed of four, or a multiple of lour. 

 " teeth or processes," and consists of three layers of cells, 

 the outer generally coloured or sculptured, the inner 

 hyaline. The inner peristome consists below of a ring of 

 80 cells, splitting up above into 16 teeth, which are 

 frequently perforated ; and two or three ciliolce often occur 

 between the teeth. In Bartramia the teeth of the inner 

 ))eristome are divided to the base into two segments ; 

 while in some plants, as Diphyscium and Btixbmtmia, the 

 inner peristome is reduced to a membrane. Tlie forms of 

 peristome are subject to great variation ; at times there is 

 only one row of teeth, at others there are two or three. 

 Owing to irregular thickenings in the cell walls, the peris- 

 tome of Barhula is beautifully twisted, while in others the 

 teeth are placed round the mouth in pairs or fours. 

 Sometimes, as in Tdraphis, true teeth are not formed, 

 but four conical masses or pseudo-teeth take their place, 

 while in Cosinodon a perforated membrane breaks up 

 with irregular teeth. The teeth are sometimes entire as 

 in Hi/pmim., divided to the middle, as in Dicranum ; or to 

 the base, as in Bacomitrium. The outer surface is frequently 

 smooth, papillose, articulate, or covered with transverse bars 

 called trabeculsB. In some plants the tips of the teeth are 

 united into a cone, as in Conostomum ; a hemisphere, as in 

 Funaria, or into a flat disk. In Cindidium the inner 

 teeth unite into a beautiful dome, and in Fontinalis into a 

 cone, while in others the teeth spread outwards on the 

 removal of the lid. The office of the peristome appears to 

 be the dispersion of the spores, at the proper time, being 

 thus analagous to the action of the elaters of Hepaticse ; 

 the latter are, however, not found in Mosses. Thus the 

 fruit spores are seen to be the result of the sexual 

 co-operation of the antheridia and archegonia, without 

 which true fruit is never produced. The formation of the 



