.282 NATURAL HISTORY OF ORGANIZED BODIES. 



As to otlier plicnoniciia of vegetal do physiology, tliey remain to a great extent 

 unexplained. Inquiry is, in a considerable measure, still confined to the verifi- 

 cation of lacts, of wbicli the interpretation has not yet been furnished. Such for 

 instance is the property possessed by the root and the stalk of vegetal)les, the 

 one of directing itself in accordance -with the teiTestrial attraction, the other of 

 reai-ing itself in the inverse direction of that attraction. Ingenious experiments 

 Avere instituted by J. Hunter and Knight with a view to arrive at the solution 

 of this problem, but the results obtained by these experimentalists have proved 

 insr.filcient to explain the facts. The action also which the light exerts upon 

 plants in curving their branches, the tendency which certain plants manifest to 

 twine themselves always in the same direction, to the right in the case of some, 

 to the left in the case of others, are facts ascertained but not explained. In a 

 word, vegetable physiology is a science which is in process of formation, but is 

 far from having attained the degree of development presented at this day by 

 animal physiology. 



In this rapid review, I have attempted to indicate the ])rincipal })hases of the 

 evolution of the natural sciences ; their succession must doubtless take place in 

 an order which may be pronounced necessary, each phase preparing the way iov 

 another, and rendering possible and productive researches which would previ- 

 ously have been premature. At the same time, the facts would certainly be 

 strained did we pretend to exhibit a succession of well-defined epochs, each exclu- 

 sively devoted to the elaboration of one of the links of this long chain. It is 

 not tlic less true however, that the hiniian mind, in the evolution of the natural 

 sciences, has pursued in general the course above indicated, a course which Ave 

 can trace in tlie advancement of all the sciences which depend upon observation 

 and experiment. 



Auguste Comte, a philosopher Avhose doctrines haA'C giA'en rise, of late years, 

 to so much discussion, has established a fact on Avhich almost all parties are in 

 accord. It is this : that the sciences which may be considered as liaA'ing reached 

 an advanced stage of maturity liaA^e passed through three successive phases ; 

 one thcolof/icalj another mdaphuskal, the \i\.^t positive. By this it is meant that 

 man, in presence of the phenomena of nature, has been led in the first instance 

 to suppose the intluence of some divinity as the permanent cause of Avhat he wit- 

 nessed ; that still later certain hidden forces or properties Avcre imagined as gov- 

 erning matter in all its manifestations of actiA-ity ; that subsequently, haAdng 

 become Avis(? enough to resist the allurements of imagination, the authority of the 

 ancients and the infiuence of routine, inquirers haA'c taken the part of accepting 

 nothin.g as true but what appeared susceptible of being demonstrated ; of renoun- 

 cing the search for first causes, and of directing their attention exclusivel}' to the 

 A-erification of facts and the deduction of laws under the control of experience. 



I advance no jn-etensions to modil'y this fornmla so ingeniously propounded by 

 Auguste Comte, still less would I A'cnture to substitute another. But placing 

 myself at the more restricted point of vicAV of the sciences Avhich have for their 

 object the facts of nature, I think it competent still farther to subdivide and 

 specify tlie phases of their evolution, and to say that in all these sciences we may 

 distinguish a certain number of periods, each corresponding to a certain stage 

 in their development. We should thus haA'C, first the period of nomenclature, 

 next that of the natural classificati(jn of beings ; still later the analytic study of 

 natural characters Avould be deA-el(.>ped, to be followed by the study of phenomena, 

 leading finally to the establishment of general laws. 



To show that the human mind has always proceeded by these steps, I shall 

 not multiply examples, but will take the most general of all. I borrow it from 

 the science which, in virtue of its comprehensiveness, takes precedence of all others, 

 the science of the universe or cosmos, of the great icliole. 



We see the immensity of space peopled Avith objects each of which is an orb 

 or heavenly bod}', and the first impulse of mankind Avas the desire to enumerate 



