378 GEOLOGICAL BIOLOGY. 



ment that ' ' tJie phnionicna of nature are regarded as one con- 

 tinuous series of causes and effects, and the ultimate object of 

 scicjice is to trace out that series.'' . . .* 



And in the same essay the remark is made that " Under one 

 aspect the result of the search after the rationale of animal 

 structure thus set afoot is Teleology, or the doctrine of adapta- 

 tion to purpose ; laider anotJier aspect it is Physiology.'' 



If we admit into the discussion of science the question as 

 to the causal relation of one thing or event to another, the 

 consideration of a supreme cause necessarily comes into 

 the case. As is tersely phrased by Whewell : ' 'In contemplating 

 the series of causes which are themselves the effects of other 

 causes, %ve are necessarily led to assume a supreme cause in the 

 order of causation, as we assume a first cause in the order of 

 succession.'"^ 



Causes not Discovered by Observation, but Discerned by the 

 Reasoning Mind. — In the scientific study of organisms it is 

 possible to separate in our minds the act of observation from 

 the act of the associating one observed fact with another as 

 cause and effect. It is one thing, however, to observe, note, 

 measure, define, and classify organisms and their structures and 

 functions, and quite another thing to state that a particular 

 structure and function is caused by a particular preceding 

 structure and function or by any other preceding conditions 

 of the world. 



For instance, there can be no dispute that the heat of the 

 sun, the various conditions of moisture, of air and soil, inci- 

 dent to the spring season, are the direct causes of the leafing 

 out of the elm-trees on the street side; but it is far from 

 the truth to say that these conditions of environment have had 

 any causative agency whatever in producing the elm leaves, 

 when the elm leaf is considered as differing from a maple 

 leaf. The mere association of two phenomena together does 

 not determine the one to be the cause of the other. 



The fact that we are familiar with and understand the 

 effects of heat and moisture, and do not understand the oper- 

 ation of the more hidden biological forces, does not influence 



*"The Crayfish," p. 3. f Nov. Org., III., x. § 7. 



