126 Papers from the Marine Biological Laboratory at Tortugas. 
A solution containing the amounts and proportions of NaCl + KCI but 
lacking magnesium and calcium is very toxic and medusz can not live for 
more than two hours in it; yet if we merely add calcium this solution will 
sustain life for more than 24 hours. 
Most important studies upon the beneficial effects of magnesium in over- 
coming the tetanus of lockjaw have been carried out by J. A. Blake, 1906, 
and by Meltzer and Auer, 1906.1 These authors find that intraspinal injec- 
tions of MgSO, in doses which do not affect the respiratory center, or other 
vital functions, are capable of abolishing, temporarily but for the time com- 
pletely, all clonic convulsions and tonic contractions in cases of human 
tetanus, and experimental tetanus produced by tetanus toxin in monkeys. 
The palliative effects of the injections may last 24 hours or longer. 
Dr. J. A. Blake, 1906,? gave five successive intraspinal injections of 4.5 
to 8 cc. of 25 to 12.5 per cent MgSO, to a boy suffering from tetanus. 
The injection was renewed whenever the relaxing effects of the previous 
dose disappeared, and a complete cure was effected in about 14 days. 
Flexner and Noguchi, 1906,* find that the fatal constituent in tetanus 
toxin is the convulsive agent tetanospasmin, which has an especial affinity 
for nervous tissue; but that certain fluorescent aniline dyes, especially eosin, 
have the power to destroy the poisonous effects of this substance. 
It would seem that the beneficial effects of magnesium in the case of 
human tetanus is due to its reducing the excitability of the nerves and 
muscles, and not to any direct effect in neutralizing the poison of the toxin. 
It would be important to know whether the tetanospasmin which pro- 
duces the convulsive tetanus has the power to precipitate magnesium or 
to produce a relative increase of the soluble calcium, for my experiments 
indicate that it is the role of magnesium to offset and neutralize the 
effects of calcium. Loeb, 1906,* states that the margin of the medusa 
Polyorchis has a tendency to remain permanently contracted in a mixture 
of NaCl + KCl + CaCl,, and this effect is due to the calcium. Loeb found, 
however, that upon the addition of MgCl, this tendency to a contracted con- 
dition lessened, and the medusa showed a more normal type of contraction. 
I find that 54m (100 NaCl + 3CaCl, + 2.2 KCl) is a powerful stimu- 
lant for Cassiopea, producing, at first, a very rapid, strong pulsation, and 
rendering the contractile tissue highly sensitive to all stimuli. The final 
effect of this solution is, however, to exhaust the tissue and produce sus- 
tained tetanus. This tetanus and exhaustion takes place even when the 
medusa is prevented from pulsating by removing its marginal sense-organs 
before it was placed in the NaCl + CaCl, + KCl. It appears that NaCl -- 
*See Meltzer, S. J., and Auer, John, 1906; Journal of Experimental Medicine, 
New York, vol. 8, p. 692-706. Also 1907; Reprints of Studies, Rockefeller Inst. Medical 
Research, New York, vol. 6, p. 692. 
* Surgery, Gynecology and Obstetrics, vol. 5, p. 541. 
* Journal of Experimental Medicine, vol. 8, p. 1. 
‘Dynamics of Living Matter, p. 9r. 
