Parsons : Flowerless Plants and their Habitats. 53 



horses, the Torruhice on chrysalides of insects buried in the ground, 

 Zasmidimn cellare forms the " cobweb " on old port wine bottles, &c, A 

 good many mosses are aquatic, but none I believe grow habitually in 

 salt water. Some mosses, and more lichens, prefer rocks near the 

 sea, and the common yellow lichen Parmelia parietina may be found 

 growing on rocks quite down to high-water mark, and indeed (as I 

 have seen) at a lower level than the upper limit attained by the sea- 

 weeds Fiicus serratiis and canaliculatus. The geographical distribution 

 of the seaweeds will no doubt yield interesting results, but my oppor- 

 tunities for observing these plants have been so few, that I am unable 

 to say anything about their favourite places of grow;th. The fresh- 

 water algge, like the fungi, depend for their occurrence chiefly upon 

 the presence of a suitable medium. The most elegant forms are found 

 in clear springs and mountain streamlets ; these are attached and 

 branched. The unattached filamentous confervoid species abound in 

 stagnant waters ; much sewage pollution however destroys them. 

 Other kinds grow on damp ground, and a few are peculiar to mineral 

 springs, as those of Bath and Harrogate. 



It is an interesting question to raise, How comes it that we find 

 special and peculiar habitats to be inhabited by special and peculiar 

 species 1 Several different answers may be suggested, each of which 

 may hold good in some instances, but not in others. In the case of 

 the lower algas and fungi, it is very probable that many of these 

 peculiar species, as they appear to be, are really only forms of other 

 commoner kinds, modified by the peculiar circumstances of their 

 place of growth — " varietates loci." In some instances, as the alpine 

 mosses on boulders in the plains, they may have been transported by 

 some means from the situations in which they usually occur ; in other 

 cases they may be outliers holding their ground under special favourable 

 circumstances amid the changed physical conditions which have altered 

 the character of the surrounding flora. In not a few cases the answer 

 must, I believe, be that the spores of such species (which we must 

 remember are produced in vast numbers), aro frequently present in 

 the .atmosphere, but that it is only very rarely that they happen to 

 fall on good ground and germinate. " Spontaneous generation " and 

 " special creation " are other answers which may be, and have been, 

 suggested ; but I have already trespassed too long upon your patience, 

 and have neither time nor inclination to enter upon these vexed 

 questions^ 



