OXYGEN CONSUMPTION IN THE PRESENCE OF CYANIDE. 409 



EXPERIMENTS ON POLYCH.ETES. 



Experiments were performed on three common polychste 

 annelids of the Atlantic coast N.ereis virens, Arenicola cristata, 

 and Chcetopterus pergamentaceus. Of the three species, Chcetop- 

 terus was found to be the most favorable for this kind of experi- 

 mentation, as it is not a very active animal. No difference in 

 amount of activity in normal and cyanide-containing sea-water 

 was observed. Arenicola was fairly favorable for the purpose 

 as it also is relatively inactive, and here again there was no 

 significant difference in activity throughout the experiments; 

 indeed, it seemed to me that the respiratory movements were 

 more pronounced in the presence of cyanide than in normal 

 sea-water. On the other hand, the results with Nereis were not 

 very satisfactory owing to the restlessness of the animals. In 

 experiments 1-3, Table V, the animals were considerably more 

 active in normal sea-water than they were after cyanide had 

 been added, and hence the decrease observed in cyanide was due 

 in part to diminished motor activity. In experiments 4-6, 

 Table V., however, differences in motor activity were not present 

 and have not contributed to the result. 



A further difficulty was encountered in the case of Nereis. It 

 was observed that both the degree of activity and the rate of oxy- 

 gen consumption of Nereis diminished when it was kept in the 

 laboratory. Experiments 1-3 were performed on freshly col- 

 lected individuals and it will be noted that the oxygen consump- 

 tion of these individuals is much higher than in the other cases, 

 and further that the recovery figures, obtained upon them twenty- 

 four hours later, are considerably lower than the original figures. 

 This is not due to the exposure to cyanide since individuals from 

 the same collection which had not been subjected to cyanide 

 showed the same decrease in oxygen intake after a day in the 

 laboratory. It is probable that this decrease is due in large part 

 to starvation. I have observed it in the case of a number of 

 other animals also, and my experience indicates that animals 

 which have been kept for a few days after removal from their 

 natural environment are preferable to freshly collected material 

 for experiments of this kind. This difficulty was not encountered 

 in the case of Chcetopterus and Arenicola since it happened that 



