INTRODUCTORY 3 



supported by the most flimsy evidence and no one at present 

 thinks of it seriously as a possible theory even. We were told 

 that there were just five races of man, and the impression was 

 left upon us that these were sharply defined. We now know 

 that this was merely Blumenbach's classification of a series of 

 closely intergrading types with every shade of color from the 

 blackest Australian to the whitest Caucasian, and that any one 

 of a dozen other classifications of race based on wider data may 

 be vastly more rational. Another unsupported dogma that we 

 learned was that there are three kingdoms of nature, the animal, 

 the vegetable, and the mineral, and thus that a fundamental dif- 

 ference existed between animals and plants. All this we are 

 obliged to unlearn and this "science falsely so-called" of our 

 early youth must retreat before the light of modern investigation. 



The establishment of the identity between what had been known 

 as animal sarcode and vegetable protoplasm, followed by the 

 propositions of Darwin and Wallace relative to the origin of 

 species gave an impetus to the study of living things which has re- 

 sulted in the building up of our present knowledge. The increased 

 use of the microscope in the study of minute forms of life, and 

 the discovery of connecting types has driven us to the con- 

 clusion that there is fundamentally no definable difference be- 

 tween animals and plants, and it is useless to attempt to manu- 

 facture distinctions where they do not exist. There is one kingdom 

 of living things, and we have come to look upon plant and animal 

 characters as simply marking tendencies which on either hand 

 become more pronounced as we pass from simple one celled 

 organisms towards those that are more highly specialized. No 

 lines drawn between the series of plant and animal forms will 

 serve as a permanent and satisfactory boundary line ; some forms 

 or some stages of development in the life history of forms will be 

 sure to overleap any such artificial boundaries, for they do not 

 exist in nature. 



If we believe, as we surely must, that the various higher forms 

 of living things have been derived from lower forms, that new 

 creations, in other words, are simply new births or growths from 

 earlier and simpler forms and so on back to the simplest organ- 

 isms that first appeared, then we should expect to find in nature 

 connecting types between one species and another, one family and 



