190 DIGESTION. 



observation, in which both hypoglossal nerves have been 

 divided, and the effect upon deglutition is very marked. The 

 animal eats with difficulty, the pieces of meat which are 

 given him frequently dropping from the mouth. He is only 

 able to swallow by jerking the head suddenly upward, so as 

 to throw the meat past the base of the tongue ; and even when 

 deglutition commences, the first steps take place slowly and 

 with apparent difficulty. The process of drinking is very 

 curious. The animal makes the usual noise in attempting 

 to drink, but the tongue does not come out of the mouth, 

 and the only way he seems to get any water is by jerking 

 the head and moving the jaw so as to throw some of the 

 liquid into the mouth. "When he attempts to drink from a 

 basin, the water is spattered in every direction. He ap- 

 pears to get more from a tall, narrow vessel. On causing 

 him to drink from a graduated glass, it was found that he 

 drank four fluid ounces in four minutes. In the case of 

 a young girl, reported to the Academy of Science, in 1718, 

 by De Jussieu, in which there was congenital absence 

 of the tongue, deglutition was impossible until the food had 

 been pushed with the finger far back into the mouth. 1 In 

 cases of amputation of the tongue, a sufficient portion of its 

 base generally remains to press against the palate and effect 

 deglutition. 



The movements in the first period of deglutition are un- 

 der the control of the will, but are generally involuntary. 

 When the food has been sufficiently masticated, it requires 

 an effort to prevent the act of swallowing. In this respect 

 the movements are like the acts of respiration ; except that 

 the imperative necessity of air in the system must, in a short 

 time, overcome any voluntary effort by which respiration is 

 arrested. 



1 DE JUSSIEU, Observation sur la manure dont une Fille sans Langue s 1 acquit 

 dcsfondions qui dependent decctorgane. Memoircs de I 1 Academic Royale des Sci- 

 ences, Paris, 1718, p. 8. 



