54 
CURT P. RICHTER 
It is hoped that further light may be thrown on the origin of 
these specific food reactions by work that is now being carried on 
by Mr. Ging Wang on the activity of the newly born of rats and 
cats before they have ever been fed. Mr. Wang is attempting to 
find out when the periodicity begins, whether or not it is present 
at birth, and what relation it has to the times of feeding, and the 
time required for the complete emptying of the stomach. He 
also hopes to get some information on these reactions during the 
period of the animal’s life before it is born. It is astonishing how 
little definite information is available at present regarding the 
activities during this very important time of development. 
The facts on hand from work on the activity of the human in¬ 
fant present certain difficulties which are not easily explained. 
Miss Wada found in her work that the gross bodily movements of 
the infant during sleep come in periods at the rate of one every 
fifty-five minutes. It is difficult to see how this rhythm could 
have been set up by any external stimuli in as much as the infant 
on which these records were taken was fed once every four hours 
from birth on. In adults the periods of activity come at the rate 
of one every two hours. But in adults we have shown definitely 
that these periods occur simultaneously with the periods of ac¬ 
tivity of the stomach. Here again, however, the relation of the 
food habits to the periods of activity is difficult to explain. 
The solution of these problems must wait for further evidence. 
REFERENCES 
(1) Szymanski, J. S.: Versuche ueber Aktivitaet und Ruhe bei Saeuglingen. 
Pfluegers Archiv, 1918, clxxii, p. 424. 
Szymanski, J. S.: Die Verteilung der Ruhe und Aktivitaetsperioden bei 
einigen Tierarten. Pfluegers Archiv, 1918, clxxii p. 430. 
Szymanski, J. S. : Aktititaet und Ruhe bei Tieren und Menschen. Zeit. f. 
Allgemeine Physiologie, 1920, xviii, p. 105. 
(2) Slonaker, J. R.: The normal activity of the white rat at different ages. 
J. Comp. Neur. and Psychol., 1907, xvii, pp. 342-359. 
Slonaker, J. R.: The normal activity of the albino rat from birth to natural 
death, its rate of growth and the duration of life. J. Animal Behav¬ 
iour, 1912, ii, pp. 20-42. 
(3) Bohn, G.: Sur les movements oscillatoires des convoluta roscoffensis. 
C. R. Ac. Sc., Oct., 1903. 
(4) Keeble, Frederick: Plant-Animals, Cambridge Manuals of Science and 
Literature, Cambridge, 1910. 
