44 
CURT P. RICHTER 
accounts for the periodicity of the action of the stomach and at 
the same time for the periodicity of the spontaneous gross bodily 
activity of the whole organism. 
Schematically this tentative formulation may be expressed in 
the following manner. Before presenting this schema, however, 
it is necessary to recall in this place several points brought out 
above in Chapter I in the experiments which deal with the 
periodic nature of spontaneous activity, when the animals were 
kept in a small cage and fed just once per day. In these experi¬ 
ments it was found that the spontaneous activity comes in regular 
periods which are separated by intervals of almost complete 
quiescence and that the activity is not evenly distributed through¬ 
out each period. There is only very slight activity at first. 
Progressively as the period goes on the activity increases until 
a maximum is reached either in the middle or toward the end of 
the period. It must also be recalled here that the stomach 
contractions are not all of the same size. Each of the contraction 
periods begins with very small contractions which involve only 
a limited part of the stomach. The contractions become larger 
and larger until the entire stomach is involved from the cardia 
to the pylorus. This maximum of activity is usually maintained 
right up to the end of each period. Following the cessation of 
the contractions the stomach becomes completely quiescent. 
The relation of spontaneous activity to the function of the stomach 
is shown schematically in figure 21. In this figure spontaneous 
activity is given on the top line while the probable relation of the 
stomach contractions to this activity is given on the second line. 
In this schema it is intended to show that the gross bodily activity 
of the organism increases progressively as the activity of the 
stomach increases. The maximum of spontaneous activity is 
reached when the whole stomach becomes involved in the con¬ 
tractions. With the cessation of the contractions of the stomach 
at the end of each period the animal becomes inactive. This 
process repeats itself with each new period of stomach contrac¬ 
tions. This relation will be discussed in more detail in the 
following chapter. 
