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central end of the n. hypoglossus to the peripheral portion of the 
nervus lingualis. The two other nerve-ends were both exstirpated as 
far as they could be reached. 
The entire cycle of experiments was the following : 
a. In a number of fullgrown hedge-hogs (14 in all) the right nervus 
hypoglossus was cut through, and the ends joined together. After a 
lapse of several days, weeks or months the animals were killed, the 
bloodvessels were rinsed hy means of the fluid of Rincur-Lockr, and 
the tissues were preserved by means of an injection of a very slightly 
alealine solution of formalin into the aorta; afterwards the nerves 
and the nerve-endings inside the tongue were stained by the 
Bre_scHowsky-method, and cross-sections or sagittal sections of the 
tongue examined under the microscope. 
The phenomena of regeneration of the motor fibers after the reunion 
of the severed ends of the n. hypoglossus I will not discuss here. 
In this connection it only interests us to know, that in preparations 
made of the tongue of animals killed 5 to 10 days after they were 
operated upon, all the fibers of the n. hypoglossus of the right half 
of the tongue were entirely degenerated, the fibers of the nervus 
lingualis having of course remained entirely intact. In this way I 
obtained a very accurate insight into the topographical relations, the 
course and distribution of both nerves throughout the tongue. These 
relations are very systematic, so that when we only take care to 
compare analogous cross-sections of different tongues with each other 
we are able to tell immediately in a given cross-section the places 
where the nerve-fibers of the n. lingualis and those of the n. hypo- 
glossus (at least the larger rami) are to be found. For a safe and 
accurate judgment of the results of the following group of experi- 
ments (6) these preliminary experiments are absolutely necessary. 
6. In another series of full-grown hedge-hogs at the right side 
of the neck the nervus lingualis and the nervus hypoglossus were 
cut through, great care being taken to make as small a wound as was 
possible and to injure no other elements. After this the central cut- 
end of the n. hypoglossus was joined with the peripheral portion 
of the n. lingualis, the two other ends were exstirpated as far as 
possible, and the wound closed. After a lapse of some weeks or 
months the animals were killed, and stained sections through the 
tongue examined after the manner described above. To prevent 
uleerative processes to occur in the lamed and anaesthetic half of 
the tongue, before the operation all the teeth of the right side of the 
mouth were stripped of their crowns. After that ulcerative processes 
in the tongue did not occur any more. 
