Report on Botany. 



161 



that these are all Ericaceous plants. Id like manner the 

 species of Podisoraa attack only the junipers on which 

 they produce the fungus galls known as Cedar apples, 

 and the black knot fungus produces its excrescences on 

 plum and cherry trees only. Each gall-producing fungus 

 has its own habitat beyond which it cannot go. 



The subject of plant fertilization continues to receive a 

 share of the attention of botanists. Without entering into 

 details let it suffice to say that the tendency of discoveries 

 in this direction is to show that self fertilization is much 

 more rare and fertilization by the agency of insects is more 

 common than has generally been supposed. Various sin- 

 gular and beautiful contrivances have been detected which 

 were evidently designed to secure cross fertilization. 

 Hence it is that some plants, when removed beyond the 

 reach of those iusects that aid in their fertilization, seldom 

 or never bear fruit unless fertilized by artificial means. 

 What a view of mutual dependence does such a fact pre- 

 sent. The plant is necessary to the insect for sustenance, 

 the insect is necessary to the plant for propagation. The 

 continuance of each depends upon the other. Who can 

 consider such intimacy and the beauty of such relations 

 and yet fail to wonder and admire ! But it is not to be 

 supposed that this mutual dependence extends to all plants. 

 By a wise provision many of those plants that have become 

 the great sources of food-supply for man aud beast are 

 exempt from the hazards of insect fertilization. The pol- 

 len of our corn fields, grain fields and meadows is sown 

 broad cast by the winds. A kind of wholesale fertilization 

 is necessary here where insects, unless they should swarm 

 in countless myriads, would be inadequate to the task. 



In a former report it was intimated that there were dif- 

 ficulties to be encountered in the study of fungi. The 

 truth of this might be inferred from the fact that although 

 we were not entirely without descriptive lists of our ferns, 



Trans. viii.~] 21 



