No. 413.] REVIEWS OF RECENT LITERATURE. 405 
the translation is generally so well done that the work, now that it is 
completed, cannot but be a boon to the English-reading student. 
p. 
Heart-Beats in Salpa. — The pulsation of the heart in three 
species of Mediterranean Salpas has been exhaustively studied by 
L. S. Schultze.! As is well known, the hearts of these animals beat 
first in one direction and then in the other. A complete set of 
advisceral or of abvisceral beats constitutes a pulsation series. The 
intervals between pulsation series are known as pauses. An advis- 
ceral pulsation series and its pause, followed by an abvisceral series 
and its pause, form a compound heart period. 
The numbers of beats in pulsation series were so extraordinarily 
variable that a normal number could not be found. The total 
number of abvisceral beats may be considerably more or less than 
that of the advisceral beats; thus in one case 247 abvisceral beats 
corresponded to roo advisceral beats, and in another 237 abvis- 
cerals to 523 adviscerals. The rates of the two sets of beats were, 
however, very close; thus 100 abvisceral beats were accomplished in 
175 seconds, and the same number of adviscerals in 174 seconds. As 
the water in which the animal was kept lost oxygen, the rate of 
beating increased; thus an individual’s heart, which at the begin- 
ning of the experiment beat 100 times in 208 seconds, after six 
hours beat the same number of times in 148 seconds. Of the three 
species studied, the two larger ones, Salpa africana-maxima and 
Cyclosalpa pinnata, had an average rate of 26 to 30 beats per 
minute; the smaller, Salpa democratica-mucronata, 107 per minute. 
The pauses between ad- and abvisceral series varied from 1 to 4 or 
occasionally 5 seconds. 
Each heart-beat is a peristaltic wave that sweeps over the heart 
from one end to the other. Usually a new wave appears at one end 
before the old one has passed off at the other, and sometimes as 
many as seven waves may be counted on a heart at once. Kruken- 
berg believed that the two ends of the heart were physiologically 
very different, and that nicotine and hellebore affected the advis- 
ceral pulsations only, the former diminishing, the latter increasing 
€m. Schultze, however, found that these poisons influence the 
ab- as well as the advisceral pulsations, and thus demonstrated that 
the ends of the heart were not in this respect dissimilar. 
* Schultze, L. S. Untersuchungen über den Herzschlag der Salpen, Jenaische 
Zeitschr. y. Naturwissenschaften, Bd. xxxv (1901), pp. 221-328, Taf. IX-XI. 
