ABNORMAL IRRITABILITY PRODUCED By Satts TOL 
Relaxation of the contracted muscle will occur when the 
muscle passes from any medium in the right column above 
to any medium in the left column. 
After the muscle has been treated for some time with any 
of the efficient solutions (Na citrate, etc.) the contractions are 
also produced when the muscle passes: 
From % or % sugar solution to air 
From 3 or % glycerin to air 
From any salt solution to air 
A very interesting and theoretically important fact is that 
the muscle loses this particular form of irritability very soon 
when it remains in contact with the air, oil, sugar solution, 
glycerin, or salt solutions different from those that produce 
this specific irritability. In LiCl or NaCl solutions the 
contact-irritability is lost as fast as, if not faster than, in a 
sugar or glycerin solution. We can re-establish the irrita- 
bility, however, if we put the muscle back into the sodium- 
citrate solution for some time. This fact, together with those 
mentioned before, suggests the following as the most prob- 
able explanation of the peculiar phenomena of contraction 
with which we have been dealing: the solutions which pro- 
duce the contact-irritability possess anions that are liable to 
form insoluble calcium compounds. They are all with one 
exception —(NH,),SO,—Na salts. Whatever the effects 
of these anions may be, the fact that in less than a minute 
the contact effects are noticeable indicates that only the sur- 
face layer of the muscle or, what is less probable, the surface 
layer of each individual fiber, is altered. It is impossible for 
the anions to migrate deeper into the muscle in so short a 
time. In the surface layer of the muscle or the individual 
fibers we have temporarily a diminution of Caions. We 
have, then, a muscle, whose surface layer differs from that of 
an ordinary excised muscle. If this layer is once established 
the muscle contracts at any change from the media of the 
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