( cxl ) 



will support a very dense population of animal as well as 

 vegetable organisms. The whole organic output is larger 

 than that of other places, and the floating population for the 

 time being of which the locality can bear the burden of 

 maintenance is greater. " Tropical luxuriance " and " arctic 

 sterility " are proverbial, and the day-flying Lepidoptera will 

 certainly be more abundant, if only because warm climates are 

 plainly more suitable than cold ones to the great majority of 

 them. 



Doubtless there is ground for the prevailing opinion that a 

 rare species is often one that is on the road to extinction, but 

 this does not account for the cases in which a species is per- 

 sistently rare though not on the whole increasing or diminishing 

 in numbers. Prof. Weismann * says it is a mistake to suppose 

 that every rare species is already in process of disappearing, 

 and expresses the opinion that a change in surrounding circum- 

 stances may cause an improvement exemplified by an increase 

 in numbers, quite independently of whether this improvement 

 is absolutely necessary to its preservation or not. 



I doubt if we have the materials yet for successfully answer- 

 ing the questions. As a possible contribution towards their 

 solution, may we entertain the thought that, like the morpho- 

 logical features before referred to, there are many actions and 

 habits of organisms that are not subjected to the Draconic 

 code summed up in the theory of the " survival of the fittest " ? 

 — that there are extensive departments of life in which a 

 milder code prevails and where many habits and many activi- 

 ties may be indulged, ministering in various degrees to the 

 enjoyments that accompany the free and healthy exercise of 

 the natural impulses — to what we know as the " joy of life." 



Scarcity may he advantageoiis. 



I venture, however, to call attention to a case in which, 

 paradoxical as it may appear, scarcity may itself be an ad- 

 vantage. The object of the enemies that prey upon insects 

 is to obtain food, and it must suit their enemies better to 

 devote themselves to the pursuit of such as are plentiful. 

 Consequently when a species is rare, and the places it haunts, 

 * " Evolution Theory," vol. i, p. 107. 



