EDWARD S. KLINE 163 



direct inhibition of cytochrome b or any component preceding cyto- 

 chrome b, we postulate that the inhibition occurs between cyto- 

 chrome b and cytochrome c, ( based on scheme in Fig. 3 ) . This part 

 of the system is not thoroughly characterized and I will not attempt 

 to expand further on the above conclusions, except to add that these 

 conclusions are similar in many ways to those drawn by Slater in 

 his work with BAL (21, 22, 23), by Potter and Reif with antimycin 

 A (18, 19, 20), and by Lightbown and Jackson with 2-heptyl-4- 

 hydroxy-quinoline N oxide ( 12 ) . 



The purified inhibitor from Hydra has toxic effects on the 

 mouse and the fiddler crab (5). When injected with the inhibitor 

 (10 micrograms per gram body weight) most or all of the fiddler 

 crabs became sluggish and about one-half of them lost their ability 

 to right themselves, when placed on their backs. Eventually some 

 of the animals died but most recovered. These effects were opposed 

 to those of the boiled inhibitor, with which little or no adverse 

 affects were noticed. We have done only a small number of experi- 

 ments of this kind, with only 5 to 6 animals in each group, thus, 

 we cannot really say much about the toxicity except that it occurs. 

 Based on the amount of inhibitor required to elicit a discernible 

 response in both the mouse and crab it does not appear that this 

 material can account for more than a portion of the potent effect 

 of toxic material present in Hydra. Welsh and Frock (25) have 

 found tetramethylammonium in Hydra littoralis. If this compound 

 is present in the nematocysts I expect that it may account for a large 

 measure of the toxins potency. 



Hydroxijindoleamines — Both hydroxyindoles and hydroxyin- 

 doleamines have been demonstrated in various coelenterates ( 14-17, 

 24, 26). One of these reports contained studies on H. oligactis (26). 

 In it, Welsh showed the presence of significant amounts of 

 5-hydroxytryptamine (serotonin) in homogenates of this animal. 

 Dr. Weissbach and I have found high concentrations of a 5-hy- 

 droxytryptamine in Hydra littoralis. We induced nematocyst dis- 

 charge by electric shock and compared the amounts of 5-hydroxyin- 

 doleamine in the Hydra medium with that present in the whole 

 animal (Table 9). This experiment showed that the discharged 

 hydroxyindoleamine was present in more than 10 times the con- 

 centration than was found in the whole animals. Several attempts 



