INTRODUCTION. 11 



This last mode of reproduction has been denominated Lucina 

 sine concubitu by the older naturalists, a term, which must not 

 be applied, as has been done by Owen, to the alternation of 

 generations, the reproduction taking place in this case under 

 totally different conditions, namely by division, by gemmation, 

 or by germ-bodies, which are not to be confounded with eggs, as 

 in all these modes of propagation the immediate influence of the 

 male fertilizing elements is wanting, and this has not been acci- 

 dentally or abnormally omitted, but, as is proved by the whole 

 course of development of these generations, remains out of action 

 in accordance with certain laws. 



As, with reference to my subsequent statements, I must lay 

 a particular stress upon the distinction between the Alternation 

 of Generations and Parthenogenesis, I repeat once more, that the 

 viviparous Aphides are not virgin females which produce eggs 

 capable of development without copulation, but that they are 

 asexual, nurse-like or larval individuals, furnished with germ- 

 stocks, which are as different as possible from the true virgin 

 female Aphides*. 



* [The author of the term ' parthenogenesis/ which was devised to replace 

 a phrase both cumbrous and incorrect, or at best only partially agreeing with 

 the phenomena referred to in the text, believed it to be, etymologically, appli- 

 cable to the male as well as the female, or the neuter. 6 napOevos is ' a young 

 unmarried man,' just as fj vap&evos is 'a maid': irapdeveia, < virginity, purity,' 

 is predicable of either sex, or of a generative individual of no sex. The term 

 'parthenogenesis' was by no means proposed, as Siebold seems to imagine, 

 under the idea that the virgin procreative Aphis was a perfect female, and its 

 brood produced from eggs. Previously to the appearance of the book so 

 entitled, Professor Owen had published the results of observations showing 

 that the virgin Aphides developed their brood from nucleated cells, forming 

 < germ-masses,' not from eggs (Lectures on Invertebrata, 1843); and the 

 difference between the larviparous virgin and the oviparous wife in the Aphis 

 tribe is given in detail. He defines < parthenogenesis' to mean ' procreation, 

 without the immediate influence of the male,' as, e.g., spontaneous fission, 

 gemmation, development from germ-cells and germ-masses, or from umm- 

 pregnated ova. Should physiologists prefer, however, to limit the term as 

 proposed by Professor Siebold, they will probably concur in the desirability of 

 some other single word as an equivalent to < Alternation of Generations. By 

 < metagenesis' is meant the sum of those changes which certain species undergo 

 in the progress, through successive individuals, from the ovum to the perfect 

 impregnating and egg-producing form.] 



