2G2 THE JOURNAL OF ]30TANT 



ill aii}^ given species ; it simply has as many as could be inserted. 

 With regard to the hybrids, if anyone else has seen hybrids ^vitll the 

 same parentage as those illustrated, but with quite a different 

 appearance, this does not disprove the correctness of our identitication. 

 We find the hybrids vary very much, more thv.u the parent species, 

 and different proportions of the parents are found in different cases. 

 Also the particular form of its species to which each parent belongs 

 affects the hybrid. 



We have examined the character sometimes used in classifying 

 these orchids — /. e. whether the tips of the leaves are flat or hooded — 

 and have found that no reliance can be placed on it, as it varies within 

 the same species. Moreover, leaves may be flat arid delicate or 

 keeled and thicker in texture in the same species, according to habitat. 

 If an O. ericetorum with thick but narrow and keeled leaves be 

 transplanted into a thoroughly shady wood, the leaves become flat and 

 delicate though remaining narrow\ Similarly, specimens of O. Fuclisii 

 in shade in a wood have the flat delicate leaves, those in a field in the 

 sun have the leaves slightly thicker and more inclined to be keeled, 

 though not as coai'se in texture as those of O. ericetorum and not 

 affected as to shape. 



It is ho[)ed that where our diagnosis of forms may not be accepted, 

 the Plate will prove useful for purposes of comparison and reference. 



THE LICHEN SYMBIOSIS. 

 By a. H. Chubcit. 



(Concluded from p. 219.) 



Taking the primarj^ somatic organization of the constituent 

 Fungus as being hypothetically a mere formless weft of septate 

 mycelium, and that of the algal constituent as being in the general 

 run of cases merely discrete cocci ('gonidia') of a Protococcoid alga, 

 with no more somatic organization than that of the Palmelloid 2:)hase 

 (itself the negation of a 'soma'), the fact that the product of the 

 synthesis may present form- factors of very definite character, should 

 imply that certain factors ma}^ be ascribed to the symbiosis. Again, 

 some general rule should be applicable to all, however much minor 

 details in size, texture, or chemical nature of the units, might make 

 for variations on the scheme. That is to say. if there is one ' sym- 

 biosis-factor,' it should be reflected in one type of soma. To what 

 extent such a generalization will hold, may be discussed fi-om the 

 the consideration of a few of the commonest and most familiar of 

 British Lichens. Owing to the favourable moist atmosphere of the 

 British Isles, such types are well represented, and little is gained 

 from appealing to any more conspicuous and divergent constructions 

 of exotic genera. 



I. For example, taking a fine form as Feltigera canina (includ- 

 ing algal protoplasts as Nosfoc) growing as beautifuUy-lobed and 

 branch 'd j^'^tches, a foot or more in diameter, the somatic organ- 



