December, 1922. 



The Canadian Field-Naturalist 



169 



larvae of beetles and other insects which attacked 

 the dead timber. Ordinarily the forests of Scot- 

 land are kept so free of decaying logs that there 

 is little material for such insect pests, and there- 

 fore no food for the birds which visited the scene 

 on that occasion. Similarly in British Columbia 

 the destruction of our forests by logging and fires 

 must be accompanied by a change in the flora and 

 finally a change of fauna. 



In his study of factors influencing the life of 

 plants, the modern botanist finds that his work 

 leads him into some branches of the sister sciences: 

 Zoology, Geology, and even Astronomy and 

 Meteorology. 



Astronomical and Meteorological Inter- 

 Relationships 

 He can show that there is a relationship between 

 sun-spots and the high cost of living. This can 

 be verified by consulting the records of sun-spots 

 and temperatures for a given number of years and 

 comparing these with the price of wheat during 

 those years. Astronomers and meteorologists have 

 observed that the occurrence of sun-spots is 

 succeeded by a spell of cold weather, this adversely 

 affects the growth of wheat and other food plants, 

 resulting in an appreciable diminution of the crop, 

 and a consequent increase in cost of the world's 

 food supplies. 



Zoological Inter-Relationships 

 To show how plants and animals are similarly 

 bound together by a web of complex relations, one 

 need only mention Darwin's classic explanation as 

 to how the Clover crop may depend on the num- 

 ber of cats in a district. Many of you are familiar 

 with the details, and I will only summarize them 

 for the benefit of those who may not have read 

 Darwin's "Origin of Species". It is well known that 

 Clover is largely dependent on Humble bees for 

 pollination. Darwin states that seventy heads 

 of Dutch Clover yielded 2290 sedes, and twenty 

 heads protected from bees produced not one. 

 One hundred heads of Red Clover produced 2700 

 seeds, and the same number of protected heads 

 produced not one single seed. The number of 

 Humble bees depends in great measure upon the 

 number of field mice, which destroy their combs 

 and nests; the number of mice depends on the 

 number of cats. Col. Newman is quoted as 

 saying that "Near villages and small towns I have 

 found the nests of humble bees more numerous 

 than elsewhere, which I attribute to the number 

 of cats that destroy mice." 



We could go further, and show that a failure of 

 the Clover crop might result in a scarcity of fodder 

 and of nectar thus preventing our fair Province 

 from becoming a land flowing with milk and honey. 



Co-Operation op Animals 

 The inter-relationships of Botany and Zoology 

 are so numerous that in studying the life of plants 

 it is also necessary to study the habits and life 

 of some animals. I have already referred to 

 pollination in the case of Clover, and if one had 

 time to discuss the pollination of some of our 

 native flowers you would find it a fascinating 

 branch of the subject. The ingenious devices or 

 adaptations of flowers to secure the visits of 

 suitable insects; and the contrivances for the ex- 

 clusion of unsuitable visitors; how flowers open, and 

 shed perfume only when suitable insects are on the 

 wing; how others hold the insect prisoner until the 

 flower is ready to li berate it, to be again imprison- 

 ed by another flower; how others set water traps, or 

 exude sticky fluid to prevent unsuitable insects 

 from robbing the nectar in the flowers; these are 

 mere incidents in the life of the plant, yet they 

 cause us to enquire into the orders of insects which 

 are suitable or unsuitable in effecting the pollina- 

 tion of different flowers. 



To illustrate how complete is the relationship 

 between insects and the structure of flowers, I 

 may mention that in studying the flora of Mada- 

 gascar, botanists discovered many flowers not 

 found in any other part of the world. Amongst 

 these was an orchid Macropledrum sesquipedale, 

 which secreted nectar at the end of a tubular 

 spur 10 to 18 inches in length. Naturalists 

 doubted the existence of any insect with a pro- 

 boscis long enough to reach the nectar, and cer- 

 tainly at that time no such insect was known. 

 Darwin, however, prophesied that a butterfly 

 would be found in the same locality with a pro- 

 boscis long enough to drain the tube; and several 

 years later a naturalist named Forbes, working in 

 the same region, confirmed the prediction by 

 discovering the insect. 



In studying the distribution of plants through- 

 out the world, we have to consider the method of 

 seed dispersal, and many plants use animals as 

 distributing agents .Botanists in all parts of the 

 world are endeavouring to ascertain the origin of 

 many genera and species of plants, and we have 

 to take into account the migration of birds and 

 other animals to ascertain if some of our British 

 Columbia species came from the north or from the 

 south. Take for example a problem which has 

 interested me for many years, namely, the origin 

 of Dogwood, Arbutus, and Cascara. These trees 

 range from California to British Columbia, they 

 all reach their northern limit in this Province, and 

 they are generally referred to as southern plants, 

 but it is just possible that they may belong to 

 British Columbia and have spread south. These 

 trees have edible fruits and the seeds are distci- 



