38 SEA-SIDE STUDIES. 



ditions attending vision "vvitli the assisted and the unassisted 

 eye are different. The microscopic observer is on his guard 

 against fallacies of interpretation which seldom suggest them- 

 selves to him when observing with the naked eye ; and this 

 critical caution makes him not only less rash in interpreting 

 appearances, but makes him anxious to verify interpretations 

 by other means. If the contradictions of observers be cited 

 as a proof of the deceptive nature of the instrument, what 

 shall we say to those manifold and jjersistent contradictions 

 of anatomists using their unassisted eyes? But in truth, 

 the controversies of microscopists have rarely turned upon 

 simple facts of appearance, they have been almost wholly 

 questions of interpretation. 



The scientific Naturalist Avill not content himself with 

 Observation, however cautious and patient ; to it he will 

 add what may be called the great mental instrument, Kxperi- 

 ment, the instrument by which we verify the accuracy of our 

 observations and conclusions, and by which Nature is inter- 

 rogated. Experimental Physiology is in its infancy ; which 

 is another way of saying that the science of life is in its 

 youth. Sciences begin in casual observation, and systematic 

 reasoning. Careless of facts, men are then careful in lo^ric 

 They build elaborate structures upon shifting sand. After- 

 wards arrives the epoch of doubt ; men become aware how 

 illusoiy is the reliance on reasoning, be it never so logical, 

 unless the data are exact, unless each step has been verified. 

 The scrutiny of facts becoming more urgent. Observation 

 ceases to l)c casual and careless ; a cultivated caution takes its 

 place, and conclusions ai-e tested less by their logical coher- 



