PHYSIOLOGY. 303 



over the study of the insect world without more than one-hundredth 

 of our native insects having been observed throughout all the conditions 

 of their existence. But he who should wonder at this apparently small 

 amount of observation will at least admit that observation is one of the 

 most difficult occupations, and that to accomplish it as much earnest- 

 ness, skill, and luck are required as patience, leisure, and industry, 

 and that the former as well as the other requisitions are not found every 

 day in everybody. We justly, therefore, admire and venerate men 

 like Reaumur, De Geer, Swammerdamm, Rbsel, Bonnet, Huber, 

 Lyonet, Rengger, Carus, Treviranus, &c., whose multifarious endea- 

 vours and labours have acquired for us the knowledge which may be 

 considered as forming the foundation of our conclusions and future 

 deductions. 



To observation, which is more subject to casual opportunity, we may 

 append EXPERIMENT, as a second means of enlarging the compass of 

 physiological knowledge. Experiment is an observation produced 

 forcibly, and consequently not so fully to be depended upon as those 

 derived from secretly watching nature ; we must therefore be more 

 cautious in experimenting, for nature constrained frequently adopts a 

 form and figure which in a state of freedom she would despise. This 

 is, namely, still more the case in the lower animals, from their possess- 

 ing a greater power of adaptation to circumstances than the higher 

 ones ; I will merely refer to Trembley's well-known experiments upon 

 the polypi, as well as to Spallanzani's history of the reviviscence of the 

 wheel animal ; which last, however, according to Ehrenberg's recent 

 observations, are untrue. This has been also the case in insects ; for 

 who would not be incredulous upon being told that the larvae of a fly 

 (Eristali.v tenax. Meig.) will admit of being pressed in a book-binder's 

 press as broad and thin as a card without being killed, when freed from 

 its confinement and returned to its usual dwelling-place ? 



200. 



Having learnt the way whereby physiological facts may be acquired, 

 we must look for a method according to which these facts may be 

 appropriately classed. If with this object we reflect upon all the 

 phenomena relating to the life of insects, we shall find a portion of 

 them refer particularly to the functions of the body, and another por- 

 tion develope higher, and, as it were, intellectual tendencies in insects. 

 To the first belong those observations which acquaint us with their 



