258 
BULLETIN OP THE BUREAU OP FISHERIES 
of quinine alone. The two substances stimulate entirely separately. Both reactions 
probably took place, but only the shorter one could be measured. 
It is to be expected that, if the two substances act on the same sensory ending, 
the effect of such a mixture would be additive and therefore cause reaction following 
a latent period shorter than that of either alone. Such is the case when mixtures of 
such salts as KC1 and NaCl are employed. Two solutions were made up as follows: 
KC1, 0.1 M.; and NaCl, 0.5 M. The latent periods of the reaction to these and to 
mixtures of the two solutions were as follows: 
Seconds 
NaCl 
1 part KCL.l 
2 parts NaClJ 
1 part KC1..1 
1 part NaCl] 
3. 69 
3. 64 
3. 59 
2 parts KCll 
1 part NaClJ 
KC1 
Seconds 
3. 52 
3.50 
The effect of the two salts in the above case was additive. It is possible to keep 
the latent period constant by replacing a part of the KC1 with the proper amount of 
NaCl. However, this is not true in the case of mixtures of quinine and cumarin, or of 
cumarin and NaCl. 
Crozier (1916) demonstrated the physiological antagonism between the salts of 
certain univalent and bivalent cations in the stimulation of the frog’s foot. Tests 
with mixtures of NaCl and MgCl 2 on stimulation of the oyster failed to demonstrate 
any antagonism. However, the high proportion of these salts in sea water would 
suffice to prevent any considerable effect of such antagonism. These tests, neverthe- 
less, are of some interest for the results seem to throw some light upon the question of 
changing latent periods. 
In Table 1 data are presented to show the results of an attempt to find the latent 
period due to mixtures of NaCl and MgCl 2 each of which had approximately the same 
effect. It will be observed that most of the values are between 2.45 and 2.65 seconds, 
but that certain of them are about one second higher. On one day the experiments 
with NaCl were made and the latent period was of the high level. On the next day 
the latent period for MgCl 2 was about the same. On the third day a mixture was 
employed and the latent period was a full second lower. It appeared as if the 
effect of the mixture had been increased, but a series of tests with NaCl gave low 
values also. During the following two days the latent periods of the reaction to 
solutions of a single salt or to mixtures remained likewise low. Two days later, 
however, the reaction time to MgCl 2 was again high, but that to a mixture was low. 
Table 1 . — Latent -periods of reaction to mixtures of NaCl ( 0.5 M) and MgCl 2 ( 0.5 M) 
Date 
Time 
Salts 
Aver- 
age 
la- 
tent 
peri- 
ods 
Tem- 
pera- 
ture 
Latent 
period 
level 
Date 
Time 
Salts 
1 Aver- 
age 
la- 
tent 
peri- 
ods 
Tem- 
pera- 
ture 
Latent 
period 
level 
Feb. 1... 
Feb. 2... 
Feb. 3— 
Feb. 4... 
10-11 a. m_ 
2- 3 p. m... 
10- 11 a. m. 
3- 4 p. m... 
11- 12 m_— 
3-4 p. m... 
NaCl 
MgCh 
/NaCl, 50 per cent. 
IMgCh, 50 per cent. 
NaCl 
MgCb 
/NaCl, 50 per cent. 
(MgCh, 50 per cent. 
3.67 
3. 65 
}2.69 
2.58 
}2. 59 
°C. 
8.7 
10.3 
9.5 
11.5 
12.3 
13.0 
High. 
Do. 
Low. 
Do. 
Do. 
Do. 
Feb. 6... 
j Feb. 7... 
11-12 m 
4-5 p. m... 
10-11 a. m. 
3-4 p. m._. 
/NaCl, 25 per cent. 
\MgCl 2 , 75 per cent. 
NaCl 
MgCh 
/NaCl, 10 per cent. 
IMgCh, 90 per cent. 
} 2 - 43 
2.45 
3. 61 
}2.40 
°C. 
11.0 
10.5 
12.5 
12.8 
Low. 
Do. 
High. 
Low. 
