AMERICAN NATURALIST 



By S. V. Cli:vkn(.kk. M. I). 



In several articles on biological subjects published during 

 the last fifteen years, I have called attention to the importance 

 of analogical reasoning in the consideration of many scien- 

 tific subjects. 



To a limited extent this process of reasoning is carried i.n 

 by scientific writers generally, but mure with reference to its 

 convenience than with a full realization of its great impor- 

 tance ; for example, the vibratory theory is made use of by 

 physicists in discussing heat, light, electricity, and sound, and 

 most authors on the correlation of forces, and modern philoso- 

 phers like Herbert Spencer endeavored to reduce universal 

 phenomena to simple terms such as the convertibility of mat- 

 ter and motion, but from first to last all these thinkers seem 

 to have missed what appears to me to be the most valuable 

 application of analogy to practical sciences. 



It does not require much thought n> concede that a house 

 built of bricks will possess the properties inherent in individ- 

 ual bricks, such as unmfhimmability, degrees of porosity, 

 impermeability to moisture and air, and even the colors of 

 the original brick, but it has taken thousands of years to 

 establish the fact that however highly differentiated the ani- 

 mal tissues may be they possess only attributes of the primi- 

 tive cell, some having one or more abilities highly developed 

 with others in abevance. 

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