502 BIOLOGY. 



thus it here again passes over into the lung, just as 

 it has passed over into a fleshy cardioid stomach, and 

 completely upwards into the feather-like tongue. 



Into this sexual lung the seminal ducts also enter, or 

 the penis, when one is present, along with the oviduct. 



3420. The ovum consists of two completely separated 

 substances, and these indeed are so distinct, that the 

 vitellus is secreted at an entirely different place to the 

 albumen, the former in the ovarium, the latter in the 

 oviduct whereas in Fishes both originated together. 



The separation cannot extend further, or else the sub- 

 stances would no longer unite with each other, and the 

 vitellus must be first mixed with the albumen, after it has 

 been completely formed, after or when it is an embryo. 

 In the Bird albumen and vitellus come together during 

 their passage out of the parent's body, or in the act of 

 being laid, and thus before the albumen has been con- 

 verted into the chick. But in the Mammalia they are 

 first completely united, subsequently to their being laid 

 i. e. during the period of lactation. 



3421. The vitellus is directly secreted from the arte- 

 ries, but the albumen from an enteroidal sac or the 

 oviduct, which is finally converted into mammary glands. 



3422. The vitellus is more a product of the thorax, 

 and is therefore formed directly into the intestine and 

 entire embryo. 



3423. The albumen is an intestinal or digestive pro- 

 duct, a solution of the organic mass into protoplasm a 

 or primary mucus. It is not fashioned itself into the 

 embryo, but is only absorbed as fluid nutriment by the 

 latter. 



3424. The shell of the ovum is the last bone, which 

 the animal deposits from the sexual blood, as being analo- 

 gous to the urine. It is an aerial product, or an analogue 

 of the feather's quill. 



3425. Even the nest of the Bird is a spiritual repetition 

 of its plumage, for in it the stalks of plants, tracheae, or 

 feathers are united into one body, which reminds us in 

 the Swallows of the Acalephse. 



