48 SYLVA AMERICANA. 



the earth, in the same manner as the yolk in an egg, becom- 

 ing the placenta, prepares the nourishment, and sends it by the 

 umbilical cord to the chick. 



From the foregoing observations, it is evident that the seeds of 

 all vegetables may be considered as eggs, from which the respec- 

 tive species are produced. Now, daily experience teaches us, that 

 no egg can produce an animal, till it be impregnated or fecundated 

 by the male ; a hen, indeed, will lay eggs, but they will prove 

 abortive, unless they are impregnated or fertilized by the male. 

 That generation precedes the birth, appears throughout universal 

 nature. In quadrupeds it does without doubt : but in fishes, it is 

 supposed by some that generation follows or comes after the 

 birth or exclusion of the eggs, and that the male sperm is emitted 

 upon the eggs after they are excluded from the matrix of the female. 

 This is demonstrable in the salmon during the spawning season. 



Physiologists have entertained a variety of opinions respecting 

 generation. After rejecting the effervescences, precipitations, 

 and other ridiculous notions of the ancients, they now seem to 

 acquiesce in two opinions. The first is that of the great Hervey, 

 who supported that the speck of life, or cicatricula, the entire 

 rudiments of the future foetus were present, perfect in all its 

 members, and that it was only requisite that the male sperm 

 should add or excite the first spirit, motion and life. His follow- 

 ers contend, that so curious and wonderful a machine as an ani- 

 mal body, could never be formed and perfected by another ma- 

 chine ; and that therefore in the ovaria of the first female there 

 must needs have been her offspring, or ova, and in them others 

 of the same kind; and so on in an infinite series through all the 

 subsequent descending generations. In a word, that in the ovaria of 

 Eve, the whole race of mankind were contained, whether, past, 

 present or future. Now allowing the infinite divisibility of matter, 

 yet it exceeds all belief, that so many myriads should be con- 

 tained in one egg. The second hypothesis is that of Leuwen- 

 hoek. He supposed that the semen masculinum contained millions 

 of animalcules, and that each of the ova, in the female ovaria, had 

 a small perforation, no bigger than to admit a single animalcule. 

 Through this small aperture an animalcule is supposed to enter ; 



