1 8 MAMMALIAN DESCENT. [Lect. L 



oj0f. On tlie other liand, in tlie tropics of the Old World, 

 to this day, the brothers of the old Mammoth have been 

 living in harmony with the Sun ; but they have thrown 

 away their cloaks, and bask, naked, in his beams. 



But, during great, sudden changes in the home or 

 feeding-ground of animals, the dilemma has again and 

 again been adaptation or extinction', in many cases 

 nothing short of metamoiyhosis has saved them from 

 death, and kept them alive in famine. 



Speaking of- metamorj)hosis, I am brought to that 

 which is, evidently, the key to the intricate wards of 

 this long-locked-up problem — I mean the descent of 

 organic t}^3es. The metamorphosis of insects — a marvel 

 always fresh and wonderful both to the man of years 

 and to the child — reveals to us the practically infinite 

 jDOSsibilities of the modifications that may take place in 

 the lifetime of a single worm-like creature. 



If we were not thoroughly familiar, from our childhood, 

 with the astounding phenomena of insect-transformation, 

 if we only knew the Grub, the Pupa, and the perfect, 

 winged Imago, separately, any assertion of such a possi- 

 bility by some far-seeing biologist, would be treated with 

 contempt, and the brand of heresy would be set upon liim. 



Such a developmentalist would fare as Bruce, the 

 traveller, fared, when lie related his adventures, telling 

 of the sights his eyes had seen — 



" All he gets for his harangue is — ' Well ! 

 ^Miat monstrous lies some travellers tell.' " 



