.282 NATURAL HISTORY OF ORGANIZED BODIES. 



As to other phenomena of vegetable ph^'siology, they remain to a great extent 

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

 cation of facts, of which the interpretation has not yet been fm-nished. Such for 

 instance is the property possessed T)y the root and the st.'ilk of vegetables, the 

 one of directing itself in accordance with the teiTcstrial attraction, the other of 

 rearing itself in the inverse direction of that attraction. Ingenious experiments 

 Avere instituted by J. Hunter and Knight with a view to an-ive at the solution 

 of this problem, but the results ol)tained by these experimentalists have proved 

 insuflicient 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 principal phases of the 

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

 an order which may be pronoimced necessary, each phase preparing the way for 

 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 the less true however, that the human mind, in the evolution of the natural 

 sciences, has pursued in general the course al>ove indicated, a course which we 

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

 and experiment. 



Auguste Comte, a philosopher whose doctrines have given rise, of late 3^ears, 

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

 accord. It is this : that the sciences which may be considered as having reached 

 an advanced stage of maturity have passed through three successive phases ; 

 one theological, another mctaphyskal, the luBt 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 influence of some divinity as the permanent cause of what he wit- 

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

 eniing matter in all its manifestations of activity ; that subsequently, having 

 become wise enough to resist the allurements of imagination, the authority of the 

 ancients and the influence of routine, inquirers have taken the part of accej^ting 

 nothing as true \mt what appeared susceptible of being demonstrated ; of renoun- 

 cing the search for first causes, and of directing their attention exclusively to the 

 verification of facts and the deduction of laws under the control of experience. 



I advance no pretensions to modify this fornuda so ingeniously propounded by 

 Auguste Comte, still less would I ventm-e to substitute another. But placing 

 myself at the more restricted point of view of the sciences which have for their 

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

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

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

 in their development. AVe should thus have, first the period of nomenclature, 

 next that of the natural classification of beings ; still later the analytic stud}' of 

 natural characters M'ould be developed, 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 boiTow 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 whole. 



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

 or heavenly body, and the first impulse of mankind was the desire to enumerate 



