1881.] On Inhibitory Excitation in the Medulla Oblongata. 27 



wide separation of species apparently very closely allied. Thus 

 Ornith. Haliphron and 0. Amphrysus, Cram., are radically different in 

 the forms of their respective harpes. P, Demoleus and P. Eritlionius, 

 so very consimilar in the shape, colours, and patterns of their wings, 

 are quite unlike in their harpes. P. Bromius, P. Nireus, and P. Phorcas 

 have the harpe of a quite different type and flan in each ! On the 

 other hand, P. Machaon and P. Arcturus are consimilar in armature ; 

 while P. Agavus and P. Hector are as wide as the poles apart ! 



It must not be forgotten that the armature of not more than a sixth 

 part of the 400 and upward described Papiliones is here represented. 

 A further prosecution of the inquiry will certainly bridge-over many 

 gaps, and supply other characteristic forms. 



IX. " On the Propagation of Inhibitory Excitation in the 

 Medulla Oblongata." By Dr. H. Kronecker acd Mr. S. 

 Meltzer, Candidate in Medicine, Berlin. Communicated 

 by Dr. Burdon Sanderson, F.R.S. Received October 18, 

 1881. 



In the Royal Academy of Science of Berlin, on the 24th January, 

 1881, a communication from us, " On the Mechanism of Deglutition 

 and its Inhibitory Nerves," was read by Professor E. clu Bois- 

 Reymond. The experiments described were performed by means of 

 a slightly inflated caoutchouc ball, fastened to the blind end of an 

 oesophageal tube, the other end of which was connected with a 

 Marey's tambour, whose lever recorded the movements on the 

 blackened surface of a rotating cylinder. The ball was introdiiced, 

 for varying distances, into the oesophagus, and the movements 

 recorded resulting from the swallowing of small quantities of fluid. 



It has previously been shown (Falk and Kronecker) that, in man 

 and in the dog, the act of deglutition proper is accomplished by the 

 quick contraction of the striated muscles, and that the draught reaches 

 the stomach even before the oesophageal contraction can make itself 

 effective. In one of our former investigations, Mr. Meltzer, by ex- 

 periments performed on himself, showed that a mouthful of water 

 reaches the stomach in less than 01 second after being swallowed, but 

 that the peristaltic action does not appear in the uppermost part of 

 the oesophagus sooner than about 1*0 second after the beginning of 

 the act of deglutition, and does not reach the stomach till 5 — 6 seconds 

 later. In the communication mentioned above, the results of still 

 more recent investigations were given. It was found that in the 

 uppermost portion of the oesophagus of man, extending about 6 — 8 



