Physiology. — “Regarding Automatic Movements of the Isolated 
Tris’ '). By Jasper TEN Carr. (Communicated by Prof. G. van 
RIJNBERK). 
(Communicated at the meeting of June. 25, 1921). 
After Sertou’s description of automatic rhythmic movements of 
the M. retractor penis (1882), numerous other organs with nonstriated 
muscle-cells have been investigated with regard to this phenomenon. 
It has been proved that the stomach, the guts, the ureters, the 
uterus, the arteries, the spleen, the bladder, the gall-bladder, and 
the oesophagus, in cold- as well as in warm-blooded animals, exhibit 
rhythmic contractions when surviving outside the body under favour- 
able circumstances. In his researches MaGnus has demonstrated that, 
as regards the gut, this faculty resides in the local nervous apparatus 
of AuwrBacH’s plexus. Since all the organs mentioned also possess 
local nervous plexus, it seems likely that also in the case of these 
organs the rhythmic contractions are attributable to an automatic 
function of those local nervous apparatus. Besides our knowledge 
of these facts justifies the assumption that other organs, provided 
with smooth muscle-cells, local nervous plexus and ganglia, are also 
capable of performing automatic rhythmic contractions. This induced 
me to experiment on the iris. This organ with an abundance of 
smooth muscles, also possesses a well-developed apparatus of ganglia, 
as has been made out by the uniform results of the most recent 
histological inquiries (LauBER 1908, Scuock 1910, PorracKk 1913). 
There was good reason to suppose, therefore, that also the isolated 
iris should be capable of executing automatic rhythmic movements. 
However, the muscles of the iris being very feeble we had to cast 
about for a technique which, with least friction, should permit a 
registration of the result as much enlarged as possible. 
With this view I made the following contrivance: A blade of 
straw was fixed to a glass bar for a lever. The fulerum was con- 
stituted by a thin slightly twisted silk thread attached to the two 
prongs of a glass fork. The iris pulled at the end of the glass lever. 
The magnification of the displacement of the free end of the straw 
) After experiments made in the Physiological Laboratory of the Amsterdam 
University. 
