A BIOLOGICAL FORECAST 303 



the special possessions of the exact sciences. As a result of these coming 

 changes we expect to see biology established in a short time as an 

 •observational science of a highly exact order. 



This general change, though characteristic of the last decade, may in 

 reality be said to be no change at all, for the experimental attack on bio- 

 logical problems had its inception in the early days of the science. Its 

 growth, however, has been limited almost entirely to the narrow field 

 of human physiology, and the physiological laboratory is now proving 

 to be a source of inspiration and help to the biologist as he faces the 

 new set of problems put before him by the experimental method. It is 

 customary to date the beginning of experimental physiology from 

 Harvey's discovery of the circulation of the blood, not because this im- 

 portant discovery was a central biological fact, but rather for the 

 reason that it was the first considerable discovery in physiology that 

 was made by a rigid application of the experimental method, a method 

 which has made possible almost all the subsequent progress in this field 

 of research. 



It is the acquisition of the experimental method that is converting 

 the old biology into the new. Never before in the history of the science 

 has there been such an expansion as the last decade has witnessed. 

 Without diminishing activity in the fields that have long been under 

 cultivation, this change has added enormously to the territory open to 

 biological investigation. We still need revised and improved catalogues 

 of the animals and plants about us, even though we now know that the 

 unit of this kind of work, the species, is a highly artificial conception 

 and that in nature all is in slow but continual flux. We need to know 

 more about the distribution of animals and plants past and present, 

 about their gross structural composition, their methods of development, 

 their mutual interdependencies, their lines of descent, and the like. 

 Biology is still a rich field for the purely observational worker, but the 

 new territory laid open by the experimental method is, to my mind, the 

 land of greatest promise. This method brings us face to face with some 

 of the most fundamental problems of the organism, the solution of 

 which, in my opinion, will yield results of the utmost importance to 

 mankind. At this stage it would be presumptuous to attempt to pre- 

 dict what these results may be. But I can not let the present moment 

 pass without hazarding a guess at a few of them. 



No organism can exist long without food. Every animal and plant 

 is appropriating materials by the chemical readjustment of which it is 

 gaining the energy necessary for its own activities. We, as organisms, 

 form no exception to this general rule. Our food, like that of other 

 omnivorous animals, comes from animal and plant sources, but ulti- 

 mately all food is drawn from the green plant. Destroy completely all 

 green plants and in a short time all other organisms on the earth would 



