460 ON GENERATION. 



not indeed animals actually, but are so potentially, are true 

 animal seeds, analogous to the seeds of vegetables, as we have 

 already demonstrated in the particular instance of the lien's egg. 

 All animals are, therefore, either viviparous or oviparous, 

 inasmuch as they all either produce a living animal in fact, or 

 an egg, rudiment, or primordium, which is an animal potentially. 



The generation of all oviparous animals may therefore be 

 referred to that of the hen's egg as a type, or at all events 

 deduced from thence without difficulty, the same things and 

 incidents that have been enumerated in connexion with the 

 common fowl being also encountered in all other oviparous 

 animals whatsoever. The various particulars in which they 

 differ one from another, or in which they agree, either gene- 

 rally, or specifically, or analogically, will be subsequently treated 

 of when we come to speak of the generation of insects and 

 the animals that arise equivocally. For as every generation 

 is a kind of way leading to the attainment of an animal form, 

 as one race of animal is more or less like or unlike another, 

 their constituent parts either agreeing or disagreeing, so does 

 it happen in respect of their mode of generation. For per- 

 fect nature, always harmonious with herself in her works, has 

 instituted similar parts for similar ends and actions : to 

 arrive at the same results, to attain the same forms, she has 

 followed the same path, and has established one and the same 

 method in the business of generation universally. 



Wherefore as we still find the same parts in the perfect or 

 two-coloured egg of every bird, so do we also observe the same 

 order and method pursued in the generation and development 

 of their embryos as we have seen in the egg of the common 

 fowl. And so also are the same things to be noted in the 

 eggs of serpents and of reptiles, or oviparous quadrupeds, 

 such as tortoises, frogs, and lizards, from all the perfect two- 

 coloured eggs of which embryos are produced and perfected in 

 the same manner. Nor is the case very different in regard to 

 fishes. But of the manner in which spiders and the Crustacea, 

 such as shrimps and crabs, and the mollusca, such as the 

 cuttlefish and calamary, arise from their eggs; of the condi- 

 tions also upon which worms and grubs first proceed from the 

 eggs of insects, which afterwards change into chrysalides or 

 aurelias, as if they reverted anew to the state of eggs, from 



