DISTURBANCE OF THE INORGANIC ENVIRONMENT 313 



It is a very significant fact, therefore, that the addition of traces of 

 soluble calcium salts to any of these solutions, whether containing 

 a calcium-precipitating acid or not, results in prompt suppression of 

 the contractions. Evidently the calcium is not required in these cases 

 to supply a nutrient to the muscular tissues, but to antagonize an 

 action of an excess of Sodium which results in abnormality of function. 

 The simultaneous action of an excess of sodium ions and a calcium- 

 precipitating anion is more effective than excess of sodium alone, 

 because the calcium already present in the tissues partially antagonizes 

 the excess of sodium in the environment. These facts led Loeb to 

 emphasise the importance of the ^| ratio in living tissues and in 

 their environment. Any pronounced increase in this ratio leads to 

 hyperirritability of nervous and muscular tissues and, in fact, as Loeb 

 has pointed out, it is only the calcium in our blood and tissue-fluids 

 which prevents all our skeletal muscles from beating rhythmically 

 like the heart. 



The fact that the heart continues to beat rhythmically in the presence 

 of the calcium in the blood, although the skeletal muscles cannot do so, 

 draws our attention to the very important fact that the effect of the 

 inorganic environment differs in different types of living tissues. This 

 fact is very strikingly illustrated by the effects of salt solutions upon 

 different parts of the swimming-bells of jellyfish. These bells, in 

 normal sea-water, are almost constantly contracting in a rhythmic 

 manner and it is by the rhythmic impetus created by the expelled water 

 that the jellyfish propels itself through the water. It was first pointed 

 out by the English Biologist Romanes that when the swimming-bell 

 of the jellyfish Gonionemus is deprived by section of its margin, the 

 center of the bell will no longer beat in sea-water, while the margin 

 continues as before to beat rhythmically. Since the margin contains 

 all the nervous ganglia of the bell Romanes concluded that the beats 

 of the swimming-bell were initiated and regulated by these nervous 

 tissues. Loeb, however, found that if the centers, with the margin 

 excised, be placed in pure sodium chloride or sodium bromide solutions 

 which are isotonic with sea-water, they will beat rhythmically just 

 as the intact bell does in sea-water. The experiment really indicates, 

 therefore, that the optimal salt-mixture for rhythmic excitation differs 

 in the nervous and the contractile 'tissues of the bell. 



Another experiment which illustrates in a very striking manner 

 the differing effects of the inorganic environment upon tissues of 

 diverse function is the following: When the last abdominal segment 

 of a recently-killed fly 1 is torn out with a pair of forceps a length 

 of intestine is usually extracted from the abdomen. The muscular 

 tissue in the intestines of the Insecta, unlike ours, is striated. If this 

 be wetted with M/6 sodium chloride solution and examined under a 



1 The species actually employed was the large Australian "bluebottle," Callophora 

 rillosa. 



