242 



Papers from the Department of Marine Biology. 

 ACIDS AND ALKALIES. 



For ascertaining the effects of acids on the luminescence of Noctiluca, 

 hydrochloric (a lipoid insoluble) and benzoic (a lipoid soluble) acids 

 were used, the solutions being made up in a neutral artificial sea-water, 

 m/2(100 NaCl+2.2 KCl+2 CaCla+lO MgClz), so as to avoid the 

 disturbing presence of the buffer phosphates and carbonates. 



Certain concentrations of these acids, n/2000 to n/4000 HCl and 

 n/4000 CeHsCOOH, cause a bright continuous glow lasting from 20 to 

 60 minutes (table 4). The glow in these solutions becomes gradually 



^The constant glow at the start is without doubt due to the dying condition of some of the 

 animals. 

 ^The normal response at the start is doubtless due to the delay in taking effect. 



brighter, stays at a maximum for some time, and then becomes gradu- 

 ally fainter. In n/4000 HCl the animals also give a normal response — 

 that is, they flash on stmiulation while they are giving a steady glow. 

 Whether it is certain animals in the solution that give the one response 

 at the same time that others are giving the other, or whether all of 

 the animals give both responses, it was not possible to determine. 

 Stronger concentrations of these acids kill the animals almost instantly, 

 while weaker concentrations have practically no effect. 



The alkalies NaOH (Upoid insoluble) and NH4OH (lipoid soluble) 

 have an effect upon luminescence similar to that of the acids, except 



