792 



end üf the conus, in some animals at the bacl< wall, on others at 

 the frontal wall. Stirling's observations have been repeatedly refuted 

 by others, and hitherto the theory generally held was that such 

 a rupture does not occur, and that what Stilling had seen 

 were only artefacta, which need occasion no surprise since 

 the conus wall, which suri'ounds the ventricle, is often extremely 

 thin. In my opinion the rupture is undeniable in the horse and I 

 connect it with the unusually rich fold formation, the presence of 

 numerous recessus and the great quantity of blood. For, owing to 

 these conditions, the resorption surface of the liquor cerebro-spinalis 

 and the degree of the power of resorption increases of the relative 

 tissues, which for an animal used for long and heavy labour and 

 therefore provided with a very powerful metabolism, cannot be 

 otherwise than of the greatest use. To this opinion I will here add 

 in passing that in none of our domestic animals are such frequent 

 disturbances of the central nervous system caused by stopping of the 

 liquor cerebro-spinalis to be met with as in the horse. 



Remarkable is the occurrence of sharply defined bundles in the 

 motory region and in the immediate neighbourhood of the central 

 canal and the lumbal and sacral medulla of ruminants and pig, as 

 also the fact that about half-way in the development the commissura 

 grisea in the cow is locally developed and at other places has still 

 to be formed. 



It is known that in human beings spinal ganglia can be seen 

 at the end of the medulla inside the dura-pocket. As regards the 

 horse I can give no information on this point because the material 

 of these animals has been prepared for the investigation. Of the 

 other animals numerous spinal ganglia occurred intra-durally only 

 in the pig (foetus) : in several, these ganglia are seen caudally from 

 the conus. It is Certainly remarkable that these ganglia, which in 

 higher levels have shifted peripherally into the foramina vertebralia, 

 have remained at the end of the medulla nearer their origin or 

 have been left behind at the end of the spinal canal. The fact that 

 they even remain within the membranes entitles us to assume that the 

 spinal ganglion cells of the terminal part of the medulla are more 

 inclined to keep their connection with the spinal cord, for which 

 reason I venture to express the possibility that the cells rich in 

 pigment as described in the horse even might be central ganglion cells. 



