LESSON 3.] INTRODUCTION. V 



LESSON III. 

 INTRODUCTION CONCLUDED. 



36. REPRODUCTION, to renew that which has been destroyed. 

 Trees are reproduced by new shoots from the roots, or from cuttings 

 or slips. Some animals, as the Lobster, Crab, &c., possess the power 

 of reproducing, or generating lost parts. In the lowest tribes of the 

 Cryptogamia, where each cell is an independent individual, every 

 one has the power of preparing within itself the reproductive germs, 

 from which new generations may arise. 



37. The GERM is the origin, or first principle ; that from which 

 any thing springs. In botany it is the ovary or seed-bud of a plant, 

 the rudiment of fruit yet in embryo. In the higher plants we find a 

 complex apparatus superadded for the purpose of aiding the early 

 development of these germs, by supplying them with nutriment pre- 

 viously elaborated by the parent; yet still this operation is of a 

 purely accessory kind, and the essential part of the process remains 

 the same. 



38. Now we shall find that although the fabric of Animals 

 appears to be formed on a plan entirely different from that of Plants, 

 and although the objects to be attained are so dissimilar, there is 

 much greater accordance amongst their elementary parts, than might 

 have been anticipated. 



39. The starting point of both is the same ; for the embryo of 

 the Animal, up to a certain grade of its development, consists, like 

 that of a Plant, of nothing else than an aggregation of cells. 



40. The lowest class of animals, the Microscopical Animalcula, 

 or the invisible inhabitants of stagnant water, appear to be identical 

 with the simple cellular plants, already referred to ( Volvox globaior). 

 The bodies of these creatures are singularly elastic, and remarkable 

 for their transparency. The whole of this class (animalcules) are 

 locomotive in a high degree, and by the means of similar organs 

 vibratile cilia. Unlike the uniform progression of the plant, these 

 creatures exhibit the most astonishing irritability. 



41. Whilst swimming along at a rapid rate of speed, pursuing 

 their prey, a portion of vegetable matter or some extraneous sub- 

 stance will arrest their career ; suddenly, they throw out the water 

 with which their interior was distended, and instantly contract to such 

 a speck as to become perfectly invisible. 



