154 UNIVERSITY OF MISSOURI BULLETIN 



now, was fundamental in the historical development of the 

 science, and the acquisition of it as a mental tool is a more 

 important gain to the student, from the standpoint of educa- 

 tion, than all the information we possess about plants. In 

 very brief outline it consists of the following steps: 1. Ob- 

 servation of facts, giving us clear individual notions or per- 

 cepts ; 2. Classification of the facts ; 3. The induction from 

 the facts of general notions or concepts, independently of all 

 preconceived ideas or personal bias ; 4. By thoughtful con- 

 templation of the facts, the framing of a shrewd guess or 

 working hypothesis as to their explanation; 5. Deductive test 

 of the hypothesis by applying it to other individual cases. 

 The sole test of the validity of a hypothesis is agreement with 

 fact. If this be found, the hypothesis becomes a theory; if 

 it be not found, the hypothesis is discarded, and another one 

 sought and tested. 



That a knowledge of plants can be obtained only by study- 

 ing plants seems to us an almost self-evident truth, though 

 even now a belated traveller on the road of knowledge occa- 

 sionally appears who argues that the laboratory is a super- 

 fluous educational fad, and wishes botany taught by lectures 

 and the reading of books about plants. But, thanks to the 

 prevailing power of truth, his days are in the yellow leaf. 

 Failure to understand the necessity for unbiased observation 

 of facts accounts for the almost absolute worthlessness of 

 early natural history, and the lack of any considerable ad- 

 vance in natural knowledge among the ancients. The early 

 botanists wasted page after page arguing about the location 

 of the heart in plants, without ever taking pains to look and 

 see whether or not plants have a heart. Plants, like animals, 

 are alive, animals have hearts, therefore, where would it be 

 reasonable to expect the plant-heart to be located? So the 

 argument ran; and the science of botany practically stood 

 still for over three hundred years, because instead of first 

 observing plants, and seeing what general inferences the 



