556 STUDIES IN GENERAL PHYSIOLOGY 



In both solutions the ciliary motion continued for more than 

 six, but less than eighteen, hours. The first solution seemed 

 to be a little more harmless than the second. Anybody who 

 has had experience with the effects of K ions on muscular 

 contraction will realize that it is out of the question to 

 expect a muscle to keep its contractility for over six hours 

 in any of these solutions. Neither was Gonionemus able to 

 contract in these solutions. These experiments certainly 

 warn us against taking it for granted that the mechanics of 

 protoplasmic motions is the same everywhere, although there 

 may be some identity up to a certain point. In the case of 

 the blastula we have to deal with very young embryonic 

 tissue, and we shall see in one of the subsequent publi- 

 cations that embryonic tissue, or rather the egg-cells, differ 

 radically from the muscles and the ganglia, as far as the 

 effects of ions are concerned. 



V. ARE THE NA IONS OF OUR BLOOD AN INDIFFERENT SUBSTANCE ? 



A pure solution of NaCl (of about 0.7 per cent.) has been 

 called the physiological salt solution, inasmuch as the tissues 

 of a frog may live in such a solution for forty-eight hours. The 

 NaCl in our blood is considered to play chiefly the r6le of 

 preventing the tissues from losing or taking up any water. 1 

 According to our opinion, the Na ions of the blood as well 

 as of the sea- water are essential for the maintenance of life- 

 phenomena. 2 A reduction of the Na ions in the blood would 

 lead to a loss of Na ions and a substitution of other ions in 

 their place in the ion proteids of the tissues. But does 

 the fact that a frog's muscle can live for about forty-eight 

 hours in a ^ n NaCl solution without being poisoned indicate 

 that a pure NaCl solution is harmless for the muscle? A 



1 HOWELL, American Journal of Physiology, Vol. II (1898), p. 47. 



2 Very recently Overton has published a similar idea, but without realizing that 

 the same idea had already been expressed and verified by me in a number of papers. 

 [1903] 



