ON THE BONES, ETC. 



rocks and the tops of the highest steeples.* But it is to man himself thai 

 this dissemination of plants is chiefly owing. He who in some sort com- 

 mands nature — who changes the desert into a beautiful landscape — who 

 lays waste whole countries, and restores them to their former fruitfulness 

 — IS the principal instrument of enriching one country with the botanical 

 treasures of all the rest. Wars, migrations, and crusades, travel, curiosity, 

 and commerce, have all contributed to store Europe with a multitude of 

 foreign productions, and to transplant our own productions into foreign 

 quarters. Almost all the culinary plants of England, and the greater 

 number of our species of corn, have reached us from Italy or the East ;t 

 America has since added some ; and it is possible that Australia may yet 

 add a few more. 



The utmost period of time to which seeds may hereby be kept, and be 

 enabled to retain their vital principle, and consequently their power of ger- 

 mination, has not been accurately determined, but we have proofs enough 

 to show that the duration may be very long. Thus, M. Triewald relates 

 that a paper of melon-seeds, found in 1762, in a cabinet of Lord Morti- 

 mer, and apparently collected in 1660, were then sown and produced 

 flowers and excellent fruit ;| and Mr, R. Gale gives an instance of a like 

 effect from similar seeds after having been kept thirty-three years. § 



M. Saint-Hilaire sowed various seeds belonging to the collection of 

 Bernard de Jussieu, forty-five years after the collection had been made. 

 They consisted of three hundred and fifty distinct species ; of these many, 

 though not the whole, proved productive. In some the cotyledon appeared 

 to have nearly, but not entirely, perished ; in which, therefore, though the 

 seeds swelled, and promised fairly at first, they died away gradually. And 

 as it is a well-known fact that melons improve from seeds that have been 

 kept for two or three years, he conceives that in this case the cotyledons 

 have been ripened during such period.il 



Animal seeds or eggs, when perfectly impregnated, appear capable of > 

 preservation as long! Bomare, indeed, affirms, that he himself found three 

 eggs, which, protected from the action of the air, had continued fresh in 

 the wall of a church in which they must have remained for a period of 

 three hundred years. 



The integument which covers seeds, eggs, insects, and worms, seldom 

 consists of more than two distinct layers, and is sometimes only a single 

 one ; but in the four classes of red-blooded animals it consists almost uni- 

 I forinly of three layers, which are as follows : first, the true skin, which lies 

 lowermost, is the basis of the whole, and may be regarded as the condensed 

 external surface of the cellular substance, with nerves, blood-vessels, and 

 absorbents interwoven in its texture ; secondly, a mucous web (rete mu- 

 cosiim), which gives the different colours to the skin, but which can only 

 be traced as a distinct layer in warm-blooded animals ; and, thirdly, the 

 cuticle, which covers the whole, and is furnished in the different classes 

 with peculiar organs for the formation and excretion of a variety of orna- 

 mental or defensive materials — as hairs, feathers, wool, and silk. 



The CUTIS, or trvb skin, is seldom uniformly thick, even in the same 

 animal : thus, in man, and other mammals, it is much thicker on the back 



♦ There is an interestine article on this subject published long since the above was deli- 

 rercd, an account of which may be found in the Journal of Science and the Arts, No. vii. p. 3, 

 t Wildenow, Principles, &c. § 367. X Phfl. Trans, vol. xliii. 



§ Id vol. xliii. II Tilloch's Phil. Mag. vol. xlii. p. 203. article of M. Saint-Hilaire. 



^ Pictionaire, art. Oeuf. 



