THE PROBLEM 43 



size, one species having a body 14 inches long, 

 with a spread of wings of quite 2 feet. 



When the Angiosperms came in so suddenly, 

 as it seems to us, in Cretaceous times, the whole 

 face of the world was changed, and flowers like 

 those with which we are now familiar everywhere 

 began to appear. This, the greatest change 

 which the Kingdom of Plants has ever known 

 almost comparable to the advent of Man in the 

 Animal record doubtless chiefly depended on the 

 simultaneous development of the higher forms 

 of insect life. This holds good, though, as 

 we all know, there are many Flowering Plants 

 which are not fertilised by insects but by the wind. 

 It is quite likely that the chief wind-fertilised 

 families, such as the catkin-bearing trees, were 

 derived from insect-fertilised ancestors, but this 

 is a matter of theory at present, and we will not 

 pursue the question. 



The arrangement of the different organs 

 in Angiospermous flowers is remarkably con- 

 stant, in spite of the infinite variety of form 

 which flowers show. Where all the parts are 

 present, we have on the outside the floral en- 

 velopes or perianth, the leaves of which may either 

 be all more or less alike as in a Lily or a Mag- 

 nolia, or, as is more often the case, may be in 

 two distinct sets, an outer, the calyx, commonly 

 green and serving for a protection to the bud, 



