THE 



POPULAR SCIENCE 

 MONTHLY. 



APRIL, 1876. 



ON THE BOEDER TERRITOEY BETWEEN THE ANI- 

 MAL AND THE VEGETABLE KE^GDOMS. 



By T. H. HUXLEY, LL. D., F. E. S. 



IN the whole history of science there is nothing more remarkable 

 than the rapidity of the growth of biological knowledge within 

 the last half century, and the extent of the modification which has 

 thereby been effected in some of the fundamental conceptions of the 

 naturalist. 



In the second edition of the "Regne Animal," published in 1828, 

 Cuvier devotes a special section to the " Division of Organized Beings 

 into Animals and Vegetables," in which the question is treated with 

 that comprehensiveness of knowledge and clear critical judgment 

 which characterize his writings, and justify us in regarding them as 

 representative expressions of the most extensive, if not the profound- 

 est, knowledge of his time. He tells us that living beings have been 

 subdivided from the earliest time into animated beings, which possess 

 sense and motion, and inanimated beings, which are devoid of these 

 functions, and simply vegetate. 



Although the roots of plants direct themselves toward moisture, 

 and their leaves toward air and light ; although the parts of some 

 plants exhibit oscillating movements without any perceptible cause, 

 and the leaves of others retract when touched, yet none of these move- 

 ments justify the ascription to plants of perception or of will. 



From the mobility of animals, Cuvier, with his characteristic par- 

 tiality for teleological reasoning, deduces the necessity of the exist- 

 ence in them of an alimentary cavity or reservoir of food, whence 

 their nutrition may be drawn by the vessels, which are a sort of in- 

 ternal roots ; and in the presence of this alimentary cavity he natu- 

 rally sees the primary and the most important distinction between 

 animals and plants. 



VOL. Tin. 41 



