188 



Papers from the Department of Marine Biology. 



POTASSIUM CYANIDE. 



The effect of KCN is of especial interest because of its power of 

 inhibiting cell oxidations. It was tested by mixing an equal volume 

 of photogenin (1 Cypridina to 25 c.c.) with the KCN solution, and 

 testing with an equal volume of photophelein (1 Cypridina to 12 c.c.) 

 after 10 minutes and after 1 hour. Table 8 gives the results. 



TABLE 8. Effect of KCN on light-production. 



In Cypridina, as in all other luminous animals which have been 

 tried (Cavernularia, Noctiluca (2), firefly, luminous bacteria), KCN is 

 practically without influence on light-production. Cavernularia juice, 

 for instance, will light for over 90 minutes in n/40 KCN. On the 

 other hand, n/1280 KCN is sufficient to completely inhibit the oxy- 

 luminescence of pyrogallol by the vegetable oxidases (see p. 230). 



SATURATION WITH SUGAR, (NH 4 ) 2 S0 4> AND NaCl. 



Saturation of a luminous mixture of photogenin and photophelein 

 with sugar or NaCl causes the light to disappear and it reappears on 

 dilution of the mixture with water. 



Since the (NH 4 ) 2 S04 used was acid, a small amount of this salt caused 

 the light to disappear and it did not reappear on dilution of the mixture 

 with water. 



Probably these phenomena are connected with the salting-out of the 

 luminous substances, although no signs of a precipitate are visible when 

 the natural secretion of Cypridina is saturated with NaCl or (NH 4 ) 2 S04. 

 As already pointed out, this result is no doubt due to the small concen- 

 trations of the substances present. 



CONCENTRATION OF PHOTOGENIN AND PHOTOPHELEIN IN CYPRIDINA. 



In the normal secretion of Cypridina there is more photogenin than 

 photophelein, as may be seen by adding fresh photophelein to the 

 normal secretion after the light has disappeared on standing. The 

 light again appears. The photophelein had been completely used up. 

 This may be shown in another way by allowing a concentrated mixture 

 of photogenin and photophelein to stand until the light disappears, and 

 then boiling one-half of the mixture. Upon mixing the two halves no 

 light results, as all the photophelein had been used up before the photo- 

 genin was destroyed in the tube boiled. 



