230 
DR. A. D. WALLER AND MR. E. W. REED ON THE 
from which the conclusion is drawn that contraction proceeds from base to apex. 
With regard to the rate of propagation of the excitatory state in the spontaneous 
beat we have no information. 
The application of two levers, 5 mm. apart, to the ventricle of the spontaneously 
beating Frog’s heart at once shows that the contraction is from base to apex, and the 
difference in time between the rise of the lever nearer to the base and that of the 
lever nearer to the apex can be measured with reasonable accuracy; this time- 
difference shows that the wave of spontaneous contraction occurring from base to 
apex has a rapidity of about 100 mm. per sec. at a temperature of 9° C. (Tracing 15). 
As regards the spontaneous beat of the Mammalian heart, a similar method led us to 
results markedly different from those we had obtained in the Frog’s heart. We have 
examined the hearts of Cats, Rabbits, Dogs, and Sheep, and find that in the spon¬ 
taneous beat of the excised organ the contraction of the apex generally appears to 
precede that of the base; in some cases we have been unable to detect any difference 
between base and apex : in only two cases have we seen the contraction of the base 
precede that of the apex. The accompanying Table, G, summarises our results upon 
this point, and we give examples of the records we have taken in Tracings 12 and 13. 
It may not be superfluous to add that we have exercised all possible caution and 
care, paying due regard to correspondence of levers, pressure of pens, and compara¬ 
tive size of contractions. 
It appears from our Table, firstly, that the rapidity of the wave is in general much 
greater in the hearts of warm-blooded animals than in that of the Frog. Secondly, 
that in Mammals it is more rapid in large hearts than in small; the maximum 
rapidity which we have accurately observed was in a Sheep’s heart, the record 
being taken 4 minutes after death by bleeding, the levers being 8 cm. apart ; the 
time-difference was '01 sec., giving a rapidity per sec. of 8 metres. Thirdly, the 
rapidity of the wave progessively decreases after excision of the heart.* 
* When we made our observations we were not acquainted with those of F. Klug (Da Bois-Reymond’s 
‘ Ai’chiv fur Physiologie,’ 1881, p. 265, and 1883, p. 398). In his first paper he stated as the probable 
conclusion to be drawn from his observations that apex precedes base in the normal systole of the hearts 
of Frogs and of Rabbits. No records are given. His method of observation was, however, not free 
from objection, and in his second paper he states that the evidence derived from his previous observations 
is of no value. The observations were made upon hearts in situ, with intact circulation, so that the 
discharge of blood by the auricle caused a movement of the ventricle which prevented the determination, 
with a sufficiently rapidly travelling surface, of the commencing ventricular contractions. 
The opinions of Haller, Senac, Arnold, and of a British Association Committee in 1843 (quoted by 
Kurschner in Wagner’s ‘ Handw. der Physiol.,’ 1844, vol. 2, p. 35), were various; they were based on 
simple inspection of the heart’s movements. 
