NOTES 365 



series, the chirps are low but gradually they become louder. 

 The "song" of one mouse this author likens to the sweet and 

 varied warbling of a canary. Every note was " clear and distinct." 



In referring to the same phenomenon, the naturalist Brehm, 2 

 attributes the following descriptions to various observers. One 

 informant states that the "song" is an irregular mixture of 

 chirps and trills with here and there a snarling, smacking sound 

 followed by a low murmur. Another describes it as a twitter 

 which is a mixture of long drawn squeaking and piping sounds 

 which may be heard at a distance of twenty paces. 



One observer noted the phenomenon only in the case of a 

 female mouse while giving birth to young, while another ob- 

 server states that only the male sings. 



The majority of those who have heard "singing" in mice have 

 assumed that it is due to a diseased condition of the lungs or of 

 the vocal organs, but conditions so diverse as pregnancy and 

 parasites in the liver have also been suggested as causes. 



The writer desires to add to the observations already reported 

 an additional record of "singing" mice. About the first of 

 December, 1 9 1 1 , while working one evening in his study, he 

 heard a series of sounds which seemed to come from above the 

 ceiling. At the time, they were thought to resemble the soft 

 chirp of a bird. 



Shortly afterward, some wild mice were needed for breeding 

 experiments and, by means of a trap, two mice, a male and a 

 female, were captured in the room. 



These animals, while being taken to the Harvard Psychological 

 Laboratory, produced sounds like those previously heard in the 

 room and they continued to do so at intervals after being placed 

 in a laboratory cage. 



A few days after their capture, the male escaped. The female 

 was mated with a tame mouse and produced, during the period 

 of observation, five litters, thirty-three individuals. None of 

 these offspring of the mating of "singing" mouse with non- 

 singing individual produced unusual sounds, nor has "singing" 

 appeared either in the second or the third (F2, F3) generations. 



2 Brehm, A. E. The Life of Animals. Chicago, 1896, p. 338. 



Additional references: Shuffeldt, R. W. Natural History of the United States. 

 1897, p. 420. Ingersoll, E. Life of Mammals. New York, 1906, p. 429. Ency- 

 clopedia Americana. Vol. 10, Mouse. New International Encyclopedia. Vol. 

 14, Mouse. Riverside Natural History. Vol. 5, p. 109. 



