Reproduction. 37 



and perhaps all those reptiles which have no bones, according to the 

 observation of M. Poupart, who thinks, that the number of hermaph- 

 rodite animals exceeds that of those which are divided into sexes; 

 Mem. del'Acad. des Sciences. These hermaphrodite insects I suspect 

 to be incapable of impregnating themselves for reasons mentioned 

 in Zoonomia, Sect. XXXIX. 6. 2. 



And, lastly, the most perfect orders of animals are propagated by 

 sexual intercourse only; which, however, does not extend to vegeta- 

 bles, as all those raised from seed produee some generations of buds or 

 bulbs, previous to their producing flowers, as occurs not only in trees, 

 but also in the annual plants. Thus three or four joints of wheat grow 

 upon each other, before that which produces a flower; which joints 

 are all separate plants growing over each other, like the buds of trees, 

 previous to the uppermost; though this happens in a few months in 

 annual plants, which requires as many years in the successive buds of 

 trees; as is further explained in Phytologia, Sect. IX. 3. 1. 



IV. Conclusion. 



Where climate is favourable, and salubrious food plentiful, there is 

 reason to believe, that the races of animals perpetually improve by 

 reproduction. The smallest microscopic animals become larger ones 

 in a short time, probably by successive reproductions, as is so distinctly 

 seen in the buds of seedling apple-trees, and in the bulbs of tulips 

 raised from seed; both which die annually, and leave behind them 

 one or many, which are more perfect than themselves, till they pro- 

 duce a sexual progeny, or flowers. To which may be added, the rapid 

 improvement of our domesticated dogs, horses, rabbits, pigeons, which 

 improve in size, or in swiftness, or in the sagacity of the sense of 

 smell, or in colour, or other properties, by sexual reproduction. 



The great Linneus having perceived the changes produced in the 

 vegetable world by sexual reproduction, has supposed that not more 

 than about sixty plants were at first created, and that all the others 

 have been formed by their solitary or sexual reproductions; and adds, 

 Suadent haec Creatoris leges a simplicibus ad composita; Gen. Plant. 



