EX VI RIB US VIVIMUS. 



Amongst Birds, the most striking case js seen in 

 the exceeding longevity, which is well ascertained, of 

 Parrots. They are undoubtedly the very highest of 

 Birds in development, and they live probably the 

 longest. The facts as to age do not however relate 

 to their normal potential longevity, we have to guess 

 that from the experiment in abnormal conditions. 



Next, as to generative expenditure.^ Since this 

 generally and clearly increases with diminished evo- 

 lution, it is not difficult to establish the contrast 

 between it and high longevity, as a general rule. The 

 Protozoa and Protophyta are exceedingly prolific, an 

 Infusorian being calculated to produce 268 millions 

 in the course of a single month (Paramecium) : 

 another 170 billions in four days, and their duration 

 of life is correspondingly of the shortest. Insects are 

 exceedingly prolific, and hence, in spite of their high 

 evolution, very short-lived. Many insects deposit 

 300,000 ova, but, what is a more important item of 

 consideration, they deposit an enormous bulk rela- 

 tively to their living matter. Compare the not far 

 distant but inferior Annelids, and they are seen to be 



' It does not appear worth while to consider asexual and sexual 

 genesis separately, where so little is to be said. But it does appear from 

 the facts that asexual genesis is less severe a tax, and therefore less 

 inimical to longevity than sexual genesis. Thus Chgetogaster and other 

 worms live and reproduce asexually in abundance, but at length sexual 

 genesis occurs and they die. It is in those cases where asexual genesis 

 pai takes of the nature of growth rather than germ-production that it 

 is least severe in its effect on longevity. 



