244 Lord Justice Fry [Jan. 23, 



generation is evaded ; and so on in gradually shortening circles (see 

 Table B), till we get the case of a Sphagnum, which produces a little 

 Sphagnum plant at the end of its leaves without protonema — whether 

 without bud, I do not know. In every case Nature seems to leave out 

 the sexual reproduction if she can help it, and directs her whole atten- 

 tion to the production of the vegetative organism — the moss plant in 

 the popular sense — which she never omits. 



Another point of comparison arises, but this time it is one of 

 contrast between the embryology of the two kingdoms. 



In animals, to again quote Prof. Milnes Marshall, " Eecapitulation 

 is not seen in all forms of development, but only in sexual develop- 

 ment, or at least only in development from the egg. In the several 

 forms of asexual development, of which budding is the most 

 frequent and the most familiar, there is no repetition of ancestral 

 phases, neither is there in cases of regeneration of lost parts." 



In mosses, on the contrary, the table last given shows that in 

 most of the modes of reproduction, the ancestral form, the algoid 

 protonema, is retained and reproduced, whereas in the growth from a 

 sexual cell, i. e. in the sporogone, the ancestral form entirely 

 disappears. 



The ^peristome, or girdle of teeth round the orifice of the capsule, 

 assumes very varying forms, often of great beauty and interest. In 

 some of the mosses it is absent, in some it consists of one ring of 

 teeth, in many of two rings, and in one foreign genus (Dawsonia) there 

 are as many as four circles of teeth. 



The object served by this complicated structure is not, perhaps, 

 very certain, but it seems to be intended to secure the retention or 

 exclusion of the spores from the spore sac in such conditions of the 

 atmosphere as will best conduce to their germination. In the gym- 

 nostomous mosses (i. e. those without peristome) it is observed that 

 the spores sometimes germinate within the capsule, an event which is 

 probably adverse to the prospects of the race. 



In some genera, as e. g. Bartramia, the teeth of the peristome are 

 erect in dry weather and convergent in wet weather ; and in such 

 cases it seems probable that the spores require dry weather when 

 first emitted. In other genera, as e. g. Bryuu, the teeth are conver- 

 gent in dry weather and expanded in wet weather : in those cases it 

 is probable that the spores require wet weather when first emitted. 



The motion of the teeth of the peristome appears to be due to the 

 action of a ring of specialised cells which surrounds the mouth of the 

 capsule at the base of the teeth ; and the opposite ways in which 

 these cells act in the same condition of moisture in different genera, 

 is a remarkable circumstance. 



To anyone who studies the subject, the immense variety as well 

 as beauty of the peristomes of mosses becomes very impressive. If 

 the sole end be the protection and extrusion of the spores in the 

 proper weather respectively, why is there this infinite wealth and 

 variety of form and of colour ? The question can be asked, but hardly 



