Prentiss, PeripJieral Netzvorks. 95 



the University of Strassburg, where I was studying as Parker 

 Fellow of Harvard University. While demonstrating with 

 methylene blue the innervation of the frog's heart, I obtained 

 several interesting preparations of the nervous elements in the 

 palate, which led me to a further investigation of their structure. 

 This investigation has enabled me not only to verify several 

 points which have been hitherto in doubt, but also to observe 

 new structures which other investigators have either overlooked 

 or have failed to demonstrate. 



In the present paper I shall first give evidence from prep- 

 arations of the normal palate to show that the fibers of the net- 

 works described are true nervous structures. And, secondly, 

 from degeneration preparations I shall endeavor to show whether 

 the cells present in these networks are sheath cells or are as 

 truly nerve cells as those of the brain and sensory ganglia. 



I. THE NERVOUS STRUCTURES OF THE PALATE. 



Preparations were obtained by injecting y, cc. of a i fc so- 

 lution of methylene blue (in normal salt solution) into the 

 abdominal vein of the frog. The animals were either rendered 

 passive by the subcutaneous injection of curare, or tied out im- 

 movable on the wooden frame shown in figure 8, p. 107. With- 

 in five or ten minutes after the appearance of the stain in the 

 integument, the palate with its nerves and vessels was dissected 

 from the roof of the mouth — an easy task, thanks to the lymph- 

 sinus lying beneath the integument. The preparation was then 

 placed epithelial side down, in a flat watch crystal and the ex- 

 posed surface moistened with the animal's blood while the 

 progress of the stain was watched under the microscope. When 

 the right degree of staining was judged to be obtained, the blood 

 and mucus were rinsed away with normal salt solution and the 

 tissue fixed with ammonium picrate. The preparations were 

 first usually mounted in glycerin, studied in the fresh condition, 

 and important details sketched with the camera lucida. They 

 could then be quickly washed in water, refixed in ammonium 

 molybdate and mounted in balsam. The molybdate method 

 gives much clearer mounts, but has this disadvantage, that the 



