PHYSIOLOGY. 491 



which branch off in a bifurcated manner from the coecum, 

 namely, the sexual intestine and the small or truncal 

 intestine. 



3029. All embryos have originally umbilical hernia?, 

 which do not originate through protrusion of the intes- 

 tines out of the abdominal cavity, but through their 

 entrance into the latter being retarded. 



3030. The umbilical herniae therefore indicate an 

 earlier condition of the animal, which has originated 

 through arrest of the development. 



3031. At birth all the enveloping membranes die, 

 and their point of liberation is called the navel or um- 

 bilicus. 



3032. The animal has originated through the um- 

 bilicus, and through this has it respired. 



3033. All animals which breathe by the anus, do so 

 properly through the navel ; animals of this kind are fun- 

 damentally umbilical animals. 



Parallelism of the Fcetus ivith the Animal Classes. 



3034. During its development the animal passes 

 through all stages of the animal kingdom. The foetus 

 is a representation of all animal classes in time. 



3035. At first it is a simple vesicle, stomach, or vitel- 

 lus, as in the Infusoria. 



3036. Then the vesicle is doubled through the al- 

 bumen and shell, and obtains an intestine, as in the 

 Corals. 



3037. It obtains a vascular system in the vitelline 

 vessels, or absorbents, like as in the Acalepha3. 



3038. With the blood-system, liver, and ovarium, the 

 embryo enters the class of bivalved Mollusca. 



3039. With the muscular heart, the testicle, and the 

 penis, into the class of Snails. 



3040. With the venous and arteriose hearts, and the 

 urinary apparatus, into the class of Cephalopods or 

 Cuttle-fish. 



3041. With the absorption of the integument, into 

 the class of Worms. 



