PREFACE 



To the "man in the street" the biologist, with his "bugs" 

 or his ' ' germs, ' ' frequently appears as a harmless but equally 

 useless individual. Thus in an issue of the "New Republic," 

 shortly after America's entrance into the world war, a serio- 

 comic writer in criticizing the action of President Wilson in 

 appointing a committee on national preparedness from the 

 National Academy of Sciences says, "I doubt if any other 

 nation ever responded to the prospect of war with a scheme 

 of national defense which included a Committee on Zoology 

 and Animal Morphology." 



What excuse then has the biologist for his existence ? What 

 can he say for the ' ' truth that is in him ' ' ? 



When half a century ago the Austrian monk, Gregor 

 Mendel, was "puttering" over his sweet peas in the garden 

 of the monastery at Briinn in the Tyrol, the world took small 

 notice of his work, little realizing that he was laying the 

 foundation stones of a science which was to place animal and 

 plant breeding on a scientific basis, and teach us how to build 

 a better race of man himself. When the English army sur- 

 geon Ross in India in 1898 was studying a microscopic organ- 

 ism in the blood of the owl, he could not foresee that his work 

 would in a few years' time virtually abolish malaria in 

 Ismailia on the Suez Canal, where in 1902 there were 1548 

 cases in a population of about 6,000; that it would render 

 possible the building of the Panama Canal, and convert 

 Havana into a health resort. 



Of what particular practical importance was Harrison's 

 discovery that a bit of nerve cord transferred from a tadpole 

 to a drop of frog's lymph would develop nerve fibres there? 

 Yet Harrison's method of making that discovery has opened 

 to science an entirely new field in the study of tissue growth, 

 both benign and malignant, has enabled us to observe the 

 growth of the cancer cell, and determine some of the con- 

 ditions of that growth, and may some day lead us to a solu- 

 tion of the cancer problem. 



When a fish embryo is developed in a solution of magnesium 

 chloride it gives rise to various malformations, most conspicu- 

 ous of which is the ' ' cyclopean eye. ' ' Of what possible value 

 to a workaday world is such a discovery? Very little in 



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