5M 



THE QUARTERLY REVIEW OF BIOLOGY 



characterizing animals and plants respec- 

 tively, may be significant as the persistent 

 relics of inorganic features, though we do 

 not know that this is true. 



Each animal or plant is an intricate 

 complex of interrelated and coordinated 

 chemical reactions continually taking 

 place within a body so adjusted to the 

 physical forces by which it is surrounded 

 as to enable these chemical reactions to be 

 carried on most advantageously. 



First of all, therefore, an animal or plant 

 is to be regarded as a natural laboratory 

 wherein are continually carried on multi- 

 tudes of chemical reactions made possible 

 through constant replenishment from the 

 air and from the soil of substances used up. 



THE BUTTERFLY AND THE UNIVERSE 



The intricate external interrelationships 

 of such a chemical complex may be under- 

 stood by a brief enumeration of the 

 contacts of a butterfly in terms of the 

 world taken as a whole. 



Young butterflies are known to us as 

 caterpillars. Caterpillars eat leaves — or 

 at least most of them eat leaves. Leaves 

 are produced by plants. In order to grow 

 plants must be supplied with water. To 

 them water comes in the form of rain. 

 Rain is moisture condensed from the air 

 passing in the form of winds above the 

 earth. Most of the moisture gets into the 

 air by evaporation from the surface of the 

 sea, which covers seven-tenths of the area 

 of the globe. 



The connection between the oceans and 

 the caterpillar chiefly depends on emana- 

 tions from the sun which provide the 

 energy by means of which the water is 

 evaporated from the surface of the sea, the 

 winds are made to blow, and the green 

 substance in the leaves of plants is enabled 

 to form organic out of inorganic sub- 

 stances. 



Day and night, and the varying seasons 



of the year, are functions of the emana- 

 tions from the sun combined with the 

 spinning of the earth about its axis and 

 its yearly course about the sun. 



Weather and climate play an important 

 part in the life of every butterfly, 

 directly, and also indirectly through their 

 action on the land and sea, sometimes 

 thousands of miles away. For instance 

 the alpine butterflies living on the moun- 

 tain tops in central Asia depend on snow 

 and rain brought in the form of water 

 vapor by the higher currents of the air 

 from the Atlantic Ocean across the plains 

 of Europe and of western Asia. 



The processes grouped under the general 

 heading of geology play a most important 

 part in the lives of all the butterflies. 

 Their caterpillars must have leaves to eat. 

 In order to produce the necessary leaves 

 plants must have food. Plant foods 

 mostly come from soils. Soils are formed 

 from the disintegration of the rocks, 

 which, under the influence of heat, cold, 

 rain, and other factors, both physical and 

 chemical, are continually breaking up 

 and being washed away as muds or sands 

 or gravels, which, lodging in the valleys, 

 provide the necessary food for plants. 



As caterpillars feed on plants, each on 

 a special kind or kinds, female butterflies 

 are expert botanists and always know 

 exactly the right plant on which to lay 

 their eggs. In addition, they are good 

 zoologists, for they are quick to recognize 

 their enemies and are expert in avoiding 

 them. At the same time, very many 

 butterflies take a keen delight in pestering 

 creatures weaker or less agile than them- 

 selves, and some of the larger ones will 

 even dart at the smaller birds, sending 

 them to cover. 



The bodies of the caterpillars and of the 

 butterflies show the most perfect adapta- 

 tion to their diverse modes of life. 



It is not necessary to carry this recital 



