and Laboratory Methods. 1389 



GENERAL PHYSIOLOGY. 



Raymond Pearl. 



Books and papers for review should be sent to Raymond Pearl, Zoological 

 Laboratory, University of Michigan, Ann Arbor, Mich. 



, „ , , The alternation in the direction of the 



Scbultze, L. S. Untersuchungen iiber den . . 



Herzschlag der Salpen. Jenaische Zeitschr. heart beat m the tunicates IS a phe- 

 f. Naturwiss. xxxv, N. F. xxviii, pp. 221- nomenon which has frequently been 

 328. Taf. ix-xi, 1901. , , , , ., , , , 



observed and described, but the present 



paper is by far the most comprehensive and detailed study of the subject which 

 has ever appeared. The work was done on several different species of the 

 transparent pelagic tunicate Sa/pa. A complete period in the activity of the nor- 

 mal heart of Salpa includes a succession of series of advisceral and abvisceral 

 pulsations, with an intervening short pause after each series. The different 

 phases of the activity of the heart vary so widely, both absolutely and relatively, 

 that it is impossible to give a normal value for any one of them. As an example 

 illustrative of this great variability may be taken the relative number of pulsations 

 in the advisceral and abvisceral series in the case of a specimen of Salpa demo- 

 cratica-nuuronata. The advisceral pulsations were to the abvisceral as lOU is to 

 115 in one individual of the colony, while in another individual of the same size 

 in the same colony the two series were related as 100 is to 45. The rate of the 

 abvisceral and advisceral pulsations is in general the same. The condition of 

 the water has a very decided influence on the activity of the heart. Stale water 

 produces an increase in the number of pulsations and an acceleration in their 

 rate. The author gives a detailed account of the phenomena observed in an 

 animal slowly dying in foul water. The most significant appearance under these 

 conditions is the loss of coordination in the heart beat. For example, abvisceral 

 and advisceral pulsations may start from opposite ends of the heart at the same 

 time and meet in the middle, neutralizing each other and disappearing. An 

 advisceral series may be extended to a great length ; in some cases to as many 

 as 241 single pulsations without any pause. A section on the effects of poisons 

 is mainly devoted to an account of the action of two drugs, nicotine and hellebore. 

 Nicotine decreases the number of advisceral pulsations, while hellebore increases it. 

 Experiments were performed to discover the source of the cardiac stimulus. 

 It was found that a heart completely isolated from the body beats in the normal 

 manner, thus showing that the cause of the pulsation is not peripheral. To test 

 the effect of the central nervous system on the heart beat, stimulation and extir- 

 pation experiments were performed. Electrical stimulation of the ganglion had 

 no effect either on the number or the rate of the pulsations. Extirpation of the 

 ganglion causes a decrease in the number of pulsations in a series, but it is shown 

 that this is not a specific effect of the removal of the nervous system, but, instead, 

 is a result of the loss of a certain amount of body substance. Experiments in 

 which the heart was cut transversely in pieces gave the result that these pieces 

 will, after a time, begin to beat rhythmically whether they are from the ends or the 

 middle region of the heart. Emptying the heart of all blood did not affect the 



