ON GENERATION. 463 



tion ; in everything else they agree ; they are both alike pri- 

 mordially vegetables, potentially they are animals. Wherefore, 

 the same theorems and conclusions, though they may appear 

 paradoxical, which we drew from the history of the egg, turn out 

 to be equally true with regard to the generation of animals 

 generally. For it is an admitted fact that all embryos, even 

 those of man, are procreated from some conception or primor- 

 dium. Let us, therefore, say that that which is called pri- 

 mordium among things arising spontaneously, and seed among 

 plants, is an egg among oviparous animals, i. e. a certain cor- 

 poreal substance, from which, through the motions and effi- 

 cacy of an internal principle, a plant or an animal of one 

 description or another is produced; but the prime conception 

 in viviparous animals is of the same precise nature, a fact 

 which we have found approved both by sense and reason. 



What we have already affirmed of the egg, viz. that it was 

 the sperma or seed of animals and analogous to the seeds of plants, 

 we now affirm of the conception, which is indeed the seed of 

 an animal, and therefore also properly called ovum or egg. 

 Because " a true seed," according to Aristotle, " is that which 

 derives its origin from the intercourse of male and female, and 

 possesses the virtues of both ; such as is the seed of all vege- 

 tables, and of some animals, in which the sexes are not distinct, 

 and is, as that which is first mingled from male and female, a 

 kind of promiscuous conception or animal ; for it has those 

 things already that are recognised of both ;" i. e. matter adapted 

 to nourish the foetus, and a plastic or formative and effective 

 virtue. And so in like manner is a conception the fruit of 

 the intercourse of male and female, and the seed of the future 

 embryo ; it therefore does not differ from an egg. 



" But that which proceeds from the generant is the cause 

 which first obtain^ the principle of generation, (i. e. it is the 

 efficient cause,) and ought to be called the geniture," 2 not the 

 seed, as is commonly done both by the vulgar and philoso- 

 phers at the present time ; because it has not that which is re- 

 quired of both the concurring agents, neither is it analogous to 

 the seeds of plants. But whatever possesses this, and corre- 

 sponds to the seeds of vegetables, that too is rightly entitled 

 egg and conception. 



1 De Gen. Anim. lib. 1, cap. 18. " Ibid. 



