io8 foiinial of Comparative Neurology and Psychology. 



palatine nerve is completely isolated from the brain and sensory 

 ganglia, it must be severed at the points a and b. 



The operation is simple and may be performed in the fol- 

 lowing manner. The frog is tied out back down upon a wood- 

 en frame nine inches long, shaped as shown in figure 8. In 

 each of the five extremities of this frame a vertical slit has been 

 cut. Three small blunt hooks attached to ten inch lengths 

 of thread were provided. The mouth of the frog is opened, a 

 hook caught into the upper jaw and the string drawn taut 

 through the anterior slit, as seen in the figure. By means of 

 a second hook the lower jaw is drawn back against the sternum 

 and the cord fastened in one of the posterior slits. The animal 

 is thus held motionless with mouth wide open. With small 

 scissors an incision one-fourth inch long is made along the 

 median line of the palate. One edge of the cut is then care- 

 fully lifted with forceps and hooked to one side, the string be- 

 ing drawn through one of the lateral slits. This exposes the 

 palatine nerve at the point where it enters the roof of the 

 mouth. (Fig, i. a\ Fig. 8). Next a small hooked needle 

 may be passed under the nerve, the blood-vessels separated 

 from it and a portion of the nerve removed. Both palatine 

 nerves may thus be severed by making but one incision, and if 

 the operation is carefully performed, without the loss of a drop 

 of blood. In a similar manner the Ramus communicans may 

 be cut at the point b (Fig. i) by making two small lateral 

 incisions. It is not necessary to sew up the incisions; in fact 

 the thread used in the stitches was found to irritate the animals 

 and in most cases the edges of the wounds were simply drawn 

 together. 



Digcncration Experiments. 



Series i. This series of operations was practically nega- 

 tive in its results. Eight animals were operated on during the 

 last week in June, 1903. Six died, before the expiration of 

 two weeks, of a skin disease which developed upon all the frogs 

 kept in the laboratory at the time. Of the two surviving indi- 

 viduals only one took the stain, and in this case very incom- 



