1042 
occur often, but not always (vide Fig. 15). As a transition to the 
stage of the periods of Luciani I found a periodical descent and 
= a 
Fig. 15. 
Fig. 16. 
TE ) : 
ascent. of the curves of the ventricles as is represented in Fig. 16. 
These two tigures originate from the same frog’s heart; the curves 
of Fig. 16 were registered somewhat less than half an hour before 
these of Fig. 15. In Fig. 15 we see in the course of the 3rd group 
at d the curves of the ventricle descending and ascending again. It 
seems as if this group was dividing itself. This 34 stage was treated 
