3J0 



transition takes place fiirilier down the oesopliagus. In the cow 

 and tlie sheep it only takes place in the snlcns oesophagens, the 

 continnation of the oesophagns in the stomach, in the goat, pig, and 

 the dog near the cardia. Bnt not only the oesophageal mnsculatnre, 

 also and even chiefl}" the ventricular smooth musculature is immen- 

 siely enlarged in the cow, where also the glandular surface is larger 

 and it seems probable to me that these differences have to explain 

 the small size of the dorsal »notor X^'' in the horse and the small 

 number of cells of the large motor type found in it. 



Although the greater part of the oesophageal red muscnlature is 

 striped and innervated by the IX, I should not be astonished if this 

 considerable quantity of red musciilalui'e in the lower part of the 

 oesophagus and stomach of the cow contained also a good deal of 

 smooth muscles with a vagal innervation. 



I have been able to control this in the bird, where the red 

 mnsculatnre of the stomach appared to be smooth. Moreover, 

 among the several hundred horses which passed the section-room I 

 found one in which the oesophagus was red also further down 

 to the place where it pierces through the diaphragm. I examined 

 the praecalamic part of tiie vagal nucleus (312 sections of 18 fi), 

 and I was struck by the fact that in this animal the shape 

 of the oblongata near tlie calamus resembles more that of the cow 

 and the pig than that of its own sort. Also here the floor of the 

 ventricle protrudes much more in its lateral portion. 



In comparison with my other series of 18 (i it appeared that the 

 nucleus keeps its maximum-size also further frontally. Whereas in 

 the normal horse the nucleus had lost its greatest size 120 sections in 

 front of the calamus, in this horse the maximum of the nucleus 

 was still found 190 sections in front of the calamus. Several cells 

 of the large motor type are found in this nucleus and in many 

 sections tlie top of the pyramid-shaped nucleus approaches the floor 

 of the ventricle more than is the case in the normal horse. 



Conseciuently it is very obvious that the vagal nucleus is the 

 largest in those animals which have a large stomach. Already 

 KosAKA and Yagita ^) have explained the large size of the dorsal 

 motor X nucleus in birds from the fact that these animals have 

 several stomach compartments. I may add to this that one compart- 

 ment, the so called muscular stomach of these animals has a con- 

 siderably^ developed red muscula,ture (which on microscopical exami- 

 nation appears to be smooth) and the dorsal motor nucleus of the 

 X in birds has many large cells. 



1) KosAKA und Yagita. Experimentelle Untersuchungen iiber den Ursprung des 

 Nervus Vagus etc. Okayama-lgakwai Zasshi No. 188. 1905. S. 2. 



