Case 8 was also in the fifth Week of development. The 

 length of the embryo was five inches, well formed. The 

 length of the extremities was about one inch, each extremity 

 consisted of a short stem and a rounded thick end part 

 without traces of fingers. The posterior extremities were 

 much shorter than the anterior, 3 with their end part not 

 separated. Behind the head three pairs of branchial slits 

 were seen, of which the anterior pair was more developed. 

 The branchial slits were very clearly seen from the side of 

 pharyngeal cavity. The degree of development of the lower 

 jaw suggested to Baer that the most interior pair of the 

 branchial slits was already closed. In the spinal cord in 

 the transverse section four strands were distinguished. 

 Half the vertebral arches were not united either among 

 themselves or to the bodies of vertebrae. The auricles were 

 very large in comparison with the ventricles. The latter 

 were still united with each other near the bulb of the 

 aorta. The liver was significantly smaller than the heart, 

 clearly divided into three lobes. The stomach was clearly 

 delineated from the intestine, giving a small bend only in 

 the region of its union with the hollow yolk stalk. After 

 the removal of liver and stomach > the primary kidneys were 

 seen in the cavity of the body along its extension. 



Case 9, an embryonic vesicle of five weeks age, Baer 

 obtained in damaged condition. The embryo was destroyed, 

 thus only the embranes could be examined. 



In case 10, the embryo was somewhat younger than the 

 previous one, but was slightly more formed than in case 8, 

 as seen in particular in the end parts of the extremities 

 and by the presence of the elbow joint. 



Case 11 presented a five-week-old embryonic vesicle 

 (Figure 33, 22-23) with chorion and densely shrunken branched 

 villi. The wall of the chorion consisted of two layers. 



3. It must be noted that Baer named them anterior and 



posterior and not upper and lower extremities, as if he 

 were underlining the identity of man's extremities with 

 the extremities of other vertebrates. 



447 



