Sinicturc of Smooth Muscle. 523 



mesentery close to the tube. They were placed in a jar containing 2000 

 c. c. of Ringer's solution, kept at a temperature of 37° C. 



2.15 p. ^[. — Placed the intestine in Ringer's solution. 



2.45 p. M. — The intestine was contracting rhythmically, so added 

 4 mg. of atropine. The peristalses stopped almost immediately. 



3.45 p. M. — The intestine was still quiet. Added 10 mg. more of 

 atropine. 



5.45 p. M. — The intestine was still quiet. Added 10 eg. of atro- 

 pine. Contraction began again in a few minutes, probably due to 

 the overdose. 



During the progress of the experiment pieces of the intestine were 

 removed, stimulated mechanically until completely contracted, then 

 fixed in Zenker's fluid. ITormal intestine from the same animal was 

 similarly fixed for control. Sections from both the normal and 

 atropinized muscle as well as the living muscle examined directly all 

 showed contraction Avaves of exactly the same form. 



The above experiment would lead one to conclude that the contrac- 

 tion waves do not depend upon nerve control. They must be trans- 

 mitted to neighboring fibers through some other connection between 

 the cells. Since the contraction waves are most distinct in muscle 

 with most complete syncytial structure, it is possible that they are 

 transmitted through the anastomoses between the fibers. However, 

 in muscle with only end to end anatomoses, the contraction waves are 

 frequently well marked. There is a possibility that the interstitial 

 connective tissue may transmit the waves. The continuity of the 

 contraction waves from circular to longitudinal coats, between which 

 there is often a rather thick layer of connective tissue, would rather 

 seem to support this view. The results of experimentation with atro- 

 pine are not absolutely conclusive, for the paralyzing effect of atro- 

 pine has been questioned. This was discussed under material and 

 methods. 



The staining reactions of contraction waves have already been 

 described. In Figs. 1, 2, 11, 23, they are shown in material stained 

 in Mallory's anilin-blue connective tissue stain, in Figs. 21, 37, in 

 material stained in Delafield's hsematoxylin eosin. 



