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 acertain 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. 
Vv. 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 réle of 
preventing the tissues from losing or taking up any water.’ 
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.” 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 § 2 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. 
2Very 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] 
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