6 PROCEEDINGS OF THE ACADEMY OF [Bioloc 



point of a percussion hammer. The primary contraction, or that which involves 

 the whole length of a fasciculus of muscle, is best seen when we strike upon 

 the region of the pectoralis major or that of the gluteus maximus. The second- 

 ary and local contraction is best developed by percussing the pectoral region 

 and the skin which covers the infra spiaatus scapular muscle. Illustrations 

 of the phenomena in question are so frequently within reach of the members 

 that Dr. M. did not consider it necessary to describe them more fully. 



Several circumstances had already convinced Dr. Mitchell that the secondary 

 contraction, described by him, was not due to the action of the non-striated 

 muscle of the skin. A very obvious and simple experimental test at once 

 referred the phenomenon in question to its proper source, the voluntary 

 muscles beneath the cuticle. 



A small rabbit was rendered insensible by the aid of chloroform, and the 

 skin was removed from the chest so as to expose the surface of the pect. 

 major muscle. Upon striking the muscle with a scalpel handle or any blunt 

 body, two distinct reactions ensued. 1st. The fasciculus of muscle which was 

 stretched by the blow, instantly and rapidly contracted and relaxed. As the 

 relaxation took place, a local contraction occurred at the point struck, so that 

 a small portion of the muscle could be seen to gather itself into a little' mound, 

 which again disappeared within from twenty seconds to half a minute. Both 

 phenomena, then, are due to the contractibility of voluntary muscular fibre. 

 Dr. Hammond, who had witnessed the experiment, and who had also seen the 

 phenomenon in question, agreed with the explanation given by Dr. M. 



2. Dr. Hammond stated that having had occasion recently to vivisect a bat, 

 (V. novaboracensis) he had observed that the heart continued to beat for some 

 minutes after the chest was laid open. Upon seizing the organ with a pair of 

 forceps a short distance above the orifice of the larger vessels, and severing the 

 connection of the heart by dividing these above the place where they were 

 compressed, pulsation still continued both in the auricles and ventricles for a 

 minute and a half. At the end of that period the heart ceased to act, and 

 could not be re-excited by pricking it with the point of a needle. On opening 

 the forceps so as to allow a little blood to escape, pulsation recommenced and 

 continued for about a minute. It then ceased and could not be excited by 

 irritation. A little more blood was then suffered to escape, and pulsation 

 immediately followed, continuing for several seoonds. The same thing was 

 repeated two or three times with a like result, until all the blood had flowed 

 out. The heart then remained perfectly quiescent ; its irritability was entirely 

 gone. Dr. Hammond regarded this experiment as tending to disprove the 

 hypothesis that the blood is the excitor of contractility in the heart. 



III. Pathology. 



1. Dr. Atlee exhibited a vesicle from an Hydatid Mole, mounted in a slide for 

 convenience of examination under the microscope. The specimen came from 

 a patient who was enormously swollen, with albuminuria to a very high degree, 

 and vomitings smelling most offensively of urine. Although but four orfive 

 months gone in her pregnancy, the uterus was above the umbilicus. The 

 mass which was spontaneously discharged from the uterus was about as large 

 as the head, and almost entirely similar to the specimen presented. A small 

 part, perhaps as large as two or three fingers, presented the usual color and 

 consistence of the placenta, while all the rest was colorless and of the consistence 

 of ordinary gelatine. All this latter portion was divided into grape-like masses 

 of vesicles full of liquid, varying in size from a pin's head to that of an or- 

 dinary marble. There was no vestige of an embryo. 



These moles are caused by what might be styled dropsy of the" villosities of 

 the chorion. The villosities of the chorion are hollow and composed of a large 

 pedicle, from which a trunk proceeds that is subdivided into many branches. 

 Each one of these ramifications terminates in a cul-de-sac. These moles are 



[March, 



