466 RELATION OF ORGANIC FORMS. 



We have also shown that the supply of new material is always fur- 

 nished by the sun. In the absence of his rays the plant may organize, 

 but can not increase, and, indeed, it was to the influence of light that the 

 green color of the first leaflets was due. All the day long, and with the 

 more activity as the day is brighter, the leaves, which are the collecting 

 organs, are absorbing material from the air ; they cease to do it at night. 

 The sunbeam enables them to take from the air carbon, hydrogen, and 

 nitrogen. They feed by day and fast at night. 



Astronomers say that the sun is the most sublime object the eye of 

 man can contemplate. They speak of his prodigious mass, and describe 

 how he compels the planets to move in obedient circles around him. To 

 the physiologist he is not less sublime. The most insignificant moss 

 that grows on the wall was called into existence by his heat, and is daily 

 fed by his light. The sunbeam is the finger of God. 



The nutrition of plants is therefore dependent on physical causes. 

 The carbonic acid required being brought to them by aerial currents, oc- 

 casioned partly by the warming influence of the sun on their leaves and 

 partly by the winds, the tendency of gases to diffuse into one another 

 aids in producing the same result. In this manner, as they exhaust the 

 surrounding air, fresh quantities are supplied, the separation of carbon 

 from it being brought about by the agency of the yellow rays. The 

 leaves, also, sometimes follow the motion of the sun, or present themselves 

 in the most favorable position under the influence of the indigo rays. 



The water requisite is obtained from the soil by the spongioles of the 

 roots. With *t there are carried into the interior of the plant the saline 

 and inorganic substances necessary for its structure. These, since they 

 are often of sparing solubility in water, will require large quantities of 

 that liquid to effect their introduction to a proper amount. During the 

 course of a summer there may pass through the system of the plant 

 perhaps many hundred times its weight of water a prodigious amount 

 when the phenomenon is considered on the great scale. 



Cuvier speaks of the inferior organisms as furnishing us with a series 

 Relation of or ^ ex P er i ments made by the hand of Nature, an idea often 

 ganisms to quoted and often admired, but which is, perhaps, scarcely con- 

 each other. gistent with enlarged conceptions of the system of the world. 

 An organism, no matter how high or low, is not in an attitude of isola^ 

 tion. It is connected by intimate bonds with those above and those be- 

 neath. It is no product of an experimental attempt, which, either on the 

 part of Nature or otherwise, has ended in failure or only partial success. 



The organic series an expression which is full of significance and full 

 of truth, for it implies the interconnection of all organic forms the or- 

 ganic series is not the result of numberless creative blunders, abortive at- 

 tempts, or freaks of Nature. It presents a far nobler aspect. Every 



