332 Proceedings of the Royal Society of Edinburgh. [Sess. 
conversely, that destruction of ganglionic cells completely arrested nerve 
development. 
As a result of these experiments, Harrison states that the essential part 
or axis cylinder of a nerve is an outgrowth from the central nervous 
system, since without the ganglionic cells no nerve fibres develop. 
In 1908 Miss Meiklejohn (18) published a preliminary note on the 
development of the plexiform nerve mechanism in the alimentary canal of 
the chick. The stain used was the silver-nitrate method of Ramon y Cajal. 
Miss Meiklejohn’s results may be tabulated as follows : — 
1. At two and a half to three days nerve cells and fibres were stained 
in the spinal cord and retina. 
2. At three to four days the staining of the nerve elements in the 
central nervous system was better marked. 
3. At four and a half to five days vagal fibres were seen in the stomach, 
and a nerve plexus of a simple character was seen in both the 
stomach and upper intestinal walls. 
4. At the fifth and sixth days the vagal fibres in the stomach were 
better marked, and the plexus in stomach and intestine more fully 
developed. 
Experimental Physiology. 
Bayliss and Starling (19) gave a full description of a series of experi- 
ments made by them on the movements and innervation of the small 
intestine. As a result of these experiments they recognised two move- 
ments, the pendulum and the peristaltic. The pendulum movements were 
described as rhythmic contractions affecting the longitudinal and circular 
muscle coats, myogenic in origin, and probably propagated by means of 
muscle fibres. The peristaltic movements were described as true co-ordinate 
reflexes, started by mechanical stimulation of the intestine, and carried out 
by means of Auerbach’s plexus. Further, it was stated that they were 
independent of the connections of the gut with the central nervous system, 
that they travelled in one direction from above down, and that they were 
abolished by the use of cocaine or nicotine, which paralysed the local nerve 
mechanism. 
The theory was also formulated that Auerbach’s plexus was a nervous 
system with two reflexes — inhibition and augmentation — the object being 
the propulsion of food. Paralysis of this nervous system by the use of 
nicotine or curare abolished the peristaltic but not the pendulum move- 
ments ; hence it was concluded that the latter were myogenic in origin. 
A joint paper by Langley and Magnus (20) dealt with the question of 
