ON GENERATION. 397 



said, the first effect of incubation is to cause dilatation of the 

 cicatricula, and the formation of the colliquament, in which the 

 blood first flushes and veins are distributed, and where the effects 

 of the native heat and the influence of the plastic power first 

 show themselves. And then, the more widely the ramifications 

 of these veins extend, in the same proportion do indications of 

 the presence of the vital power and vegetative force appear. 

 For every effect is a clear evidence of its efficient cause. 



In a word I say, from the cicatricula (in which the first 

 trace of the native heat appears) proceeds the entire process of 

 generation ; from the heart the whole chick, and from the um- 

 bilical vessels the whole of the membranes called secundines 

 that surround it. We therefore conclude that the parts of the 

 embryo are severally subordinate, and that life is first derived 

 from the heart. 



EXERCISE THE FIFTY-FOURTH. 



Of the order of the parts in Generation from an egg, according 

 to Fabricius. 



Having already determined what part is to be esteemed the 

 first, the blood, to wit, with its receptacles, the heart, veins, and 

 arteries, the next thing we have to do is to speak of the rest 

 of the parts of the body and of the order and manner of their 

 generation. 



Fabricius, in whose footsteps we have resolved to tread, in 

 speaking of the generation of the chick in ovo, passes in review 

 the actions which take place in the egg, and by the effect of 

 which the parts are produced, discussing them seriatim,) as if a 

 clearer view were thence to be obtained of the order or sequence 

 of generation. " There are three primary actions," he says, 1 

 which present themselves in the egg of the bird : 1st, the 

 generation of the embryo; 2d, its growth; 3d, its nourish- 

 ment. The first, or generation, is the proper action of the 

 egg; the second and third, viz. growth and nutrition, go on 



1 Op. supra cit. p. 41. 



