NATURAL HISTORY OF ORGANIZED BODIES. 283 



tliem. Artificial gronps or constellations were first cstablislicd, constituting a 

 true nomenclature of the stars. Afterwards the effort was to classify them, and 

 tlie stars wliicli appear fixed were distinguislicd from tLoso wliicli cxliibit move- 

 ment ; among these last again, the planets, the comets, and the asteroids were to 

 be distinguished before the immutable laws of the planetary movements could be 

 discovered. In this classification the terrestrial globe becam.c an individual per- 

 taining to the genus planet and a member of that class called the soJar sfjsieni. 

 It will be seen further, that the earth, considered individually, was submitted to 

 the same analysis as the individuals which pertain to the organized world. Thus 

 the eartli has its descriptive anatomy ; it is the physical geography which teaches 

 us the general arrangement of the planet, its doul)le polar oblateness, the con- 

 figuration of the land and seas, the altitude of the ground and depth of the waters 

 in difierent places, the course of the rivers which traverse the terrestrial suiface 

 like the veins in our organs. The earth has also its anatouuj of structure. This 

 is represented by geology, properly so called, which, according to the composi- 

 tion or arrangement of the formations, refers them to different types, as is done 

 with regard to the living tissues. The geologist, like the anatomist, does not 

 confine himself to the exterior appearance, but subjects each part to cliemical 

 anal3'sis, explores the densities and cohesions, observes with the microscope the 

 details, of structure, &c. Embrijogcmj itself finds its analogue in the science 

 which is occupied with the evolution of our globe and the genesis of the differ- 

 ent terrestrial strata. On one part and the other, we have the same method, the 

 same induction from what is passing under our tyes to v.'hat must have passed 

 at an epocli inaccessible to our observation. 



Thus we observe, in regard to the material study of om- planet, a striking- 

 similitude between the methods employed and those to which naturalists have 

 recourse for the study of organized beings. Without forcing the comparison, it 

 may be carried even further. The earth has functions ; there are phenomena 

 which take place in it that bear an analogy to actual life. As the moon has been 

 called the cadaver of a planet, it may be said that the earth is a living planet. 

 Under this point of view, we shall see that it has also \\.^ pligsiologg. 



It is meteorology which reveals to us the functions of our planet. In the inge- 

 nious treatise lately published on this subject by M. Marie — Davy, there may be 

 found a particularly vivid picture of that perpetual circulation of the waters v.hich, 

 quitting the sea under the form of vapor, rise into the atmosphere only to be con- 

 densed in clouds, and, falling again upon the earth, are borne by the brooks and 

 rivers to the sea from which they were separated. The atmosphere is the seat 

 of an analogous aerial circulation ; the equatorial zone is the common goal of 

 the lower trade-winds, as it is the point of departure of the Avinds of an opposite 

 direction, the upper trade-winds, which flow thence to the polar regions, whence 

 they will again return towards the equator. The distribution of terrestrial heat 

 presents a perfect resemblance to that of animal heat ; the same tendency on 

 either part to the refrigeration of the points remote from the central region : the 

 same transference of caloric by the circulation of heated liquids. Could we enter 

 here upon the study of the distribution of the animal temperature, it would be 

 seen that the analogies are still more striking than the present occasion permits 

 us to demonstrate. 



If I have dwelt at some length on this retrospective survey of the progress of 

 the sciences, it is because I have thought that much instruction might be found 

 therein for those who are seeking to advance them ; and should I have succeeded 

 in showing that the methods followed are always nearly the same, the history 

 of the progress achieved may enlighten us as to the value of each of those methods. 

 Thus, as I said in commencing, the experience acquired by our predecessors will 

 serve to conduct us in the new route Avhich we shall have to traverse. That 

 route is plainly traced ; it is easy to see that the tendency is no longer to classi- 

 fications, which will, of themselves, become perfect under the influence of ulte- 



