266 ANNUAL OF SCIENTIFIC DISCOVERY. 



processes are always synonymous, many poisons proving fatal without 

 any dissemination at all. 



Mr. Blake observed the following method : Having provided a deli- 

 cate measure of the condition of the Circulating system, by inserting 

 into the femoral artery of the animal to be experimented on Poiseulle's 

 haernadynamomete? (an instrument for measuring the rapidity of the 

 circulation), he proceeded to ascertain the time required for the pas- 

 sage of the poisons from one part of the system to the other. This he 

 effected chiefly by introducing various substances, previously known 

 to paralyze the heart, directly into the vessels, and, by means of the 

 instrument, noting the instant of time at which the first effects of the 

 poison manifested themselves, and at which the heart ceased to beat. 

 Without entering into a minute account of the experiments them- 

 selves, it may suffice to state that, in the dog, the time required for a 

 poison to pass from the jugular vein to the lungs was four seconds, or 

 from four to six seconds ; from the jugular vein to the coronary arte- 

 ries of the heart, seven seconds ; from the jugular vein to the carotid 

 artery, five to seven seconds, and from the aorta to the capillaries, four 

 seconds. A poison introduced into the jugular vein was distributed 

 through the whole body in nine seconds. In the horse, the time re- 

 quired for the completion of the circulation was from twelve to twenty 

 seconds, or somewhat less than the time (twenty-five seconds) deduced 

 by Hering, of Stuttgardt, from his experiment. These experiments 

 are in harmony with the more recent case of M. Claude Bernard. A 

 saturated solution of sulphuretted hydrogen, introduced into the jugu- 

 lar vein of a dog, began to be eliminated from the lungs in three sec- 

 onds ; and when injected into the femoral vein of the same dog, in six 

 seconds. 



ARE THE NERVES EXCITORS OR CONTROLLERS? 



Owing to the excessive complexity of the vital mechanism, our in- 

 genuity is severely taxed in every attempt to arrive at the precise 

 function of each organ in its relation to others. The observation 

 which to-day seems conclusive, may become dubious to-morrow, and 

 rejected the day after, when more accurate experiments reveal the 

 source of fallacy. This being so, we hear with little surprise that the 

 most brilliant physiologist of the day, Claude Bernard, has been led to 

 doubt the truth of what has been considered indubitable ever since 

 the nervous system has been systematically investigated, namely, 

 that nerves are excitors, their functions being to excite the activity of 

 the muscles and glands to which they are distributed. His words 

 are these : " May it not be, that we have formed false ideas relative 

 to the influence of nerves in provoking the activity of organs? In- 

 stead of being excitors, nerves are only bridles; the organs, whose 

 functional power is in some sort idio-organic, can only manifest that 

 power at the moment when the nervous influence is suspended." It is 

 certain that a perfectly quiescent muscle is thrown into activity by a 

 stimulus applied to its nerve. M. Bernard, perhaps, means his re- 

 marks to refer only to glands, since he makes no mention of the activ- 

 ity of muscles. 



