CHAPTER XXIV 

 DISCOVERIES WITH THE MICROSCOPE 



Hypotheses. — Discoveries with the microscope are Hke 

 most other discoveries in science — they usually come in the 

 course of planned work, and by the aid of hypotheses. 

 Hypotheses may be classed as unused hypotheses, and 

 working hypotheses. A new hypothesis is, or should be, 

 the best guess a capable worker can make. If it stops there, 

 it is an unused hypothesis. A new hypothesis before 

 it becomes current should first be confronted with the 

 relevant facts. This is work for the originator of the 

 hypothesis. If the hypothesis fits the relevant facts, 

 it can then be used and put to work. The work required 

 is that of prediction. A hypothesis which gives successful 

 predictions is a satisfactory working hypothesis. When 

 generally accepted, it becomes a theory. A theory is 

 useful as long as it enables predictions to be made. 



Methods of Discovery. — To the writer, it seems (as it 

 did to the greatest naturalist of last century) that the most 

 profitable kind of investigation is usually that which is 

 guided by some working hypothesis — that is, a hypothesis 

 which has already been confronted with the known relevant 

 facts. Hence, the first kind of investigation is that 

 undertaken into the unknown with the guidance of an 

 important new working hypothesis. Another kind of 

 investigation is that which aims at the confirmation or 

 extension of other work. This is both useful and necessary. 

 Confirmations of a great, new theory, Hke that of Mendel, 

 are usually of the nature of extensions. This is a safe and 

 sure method of investigation, and the results are rarely 

 without value. Another method of discovery, which may 

 be particularly fruitful, is the invention and application 

 of a new method of investigation, such as Koch's use of the 



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