VIII. MUSCLES AND NERVES. 805 



3799. Methods of Physiological Experiments and 

 Vivisections. Methodik der physiologischen Experimente und 

 Vivisectionen, von E. Cyon ; with Atlas, published by Ricker, of 

 Giessen and Petersburg, 1876. 



Physiological Institute, Leipzig {Prof. Kronecker}. 



3800. Apparatus for demonstrating the Pulsations of 

 the Prog's Heart. Physiological Institute, Leipzig. 



3801. Canula for the frog's heart apparatus. 



Physiological Institute, Leipzig. 



3802. Pendulum Commutator. 



Physiological Institute, Leipzig. 



3803. Double Myoscope for the examination and demon- 

 stration of the laws of muscular contraction. 



Physiological Institute, Prague. 



The apparatus allows two nerves to be placed in a damp chamber, at the 

 same time in opposite directions, and to be traversed by the same electrical 

 current. The contractions of the muscles connected with them may be read 

 on two dials. 



3 8 03 a. Dr. Sib son's Improved Gastric Canulse. 



3804. Professor Poster's Levers for recording the Move- 

 ments of the Muscles, Nerves, &c. T. Hawksley. 



3805. Different Modifications of the Spring Myograph 



of Du Bois-Reymond. Professor Theodore Schwann, Liege. 



A diapason or sounding fork is added, with a hammer to make it vibrate. 

 By turning the handle placed on the left-hand side the hammer is freed in the 

 first instance, and in the following moment the blackened glass plate. Ex- 

 citation is caused by means of an induction coil. Previous to the freeing of 

 the glass plate, and at the commencement of its motion, the current from the 

 pile is interrupted, because it has to pass through the small insulated spring 

 placed underneath the frame, and through the frame itself. But the latter 

 has fixed to its under edge, on the right-hand side, a small ivory plate, which 

 interrupts the metallic continuity. The excitement takes place just as the 

 frame commences, in its motion, to touch with its brass surface this spring. 

 An instrument fixed to the rod which carries the muscle enables the hori- 

 zontal and the curved line of the muscle to be traced during the same 

 experiment. Various other modifications of detail. 



3806. Muscular Balance. 



Professor Theodore Schwann, Liege. 



This apparatus was exhibited to the meeting of German naturalists at Jena 

 in 1836. It is intended to demonstrate that muscular contraction takes place 

 in accordance with the laws of elastic bodies. At that time the means of 

 producing the continuous contraction of a muscle were not known. In 

 order to determine the degree of contraction without a load or with increasing 



