412 



L. H. HYMAN. 



TABLE VI. 



ACTION OF POTASSIUM CYANIDE ON THE OXYGEN CONSUMPTION OF LEECHES 



(Hamopis marmoratls, EXPS. 4 AND 7, AND Herpobdella punctata, 



REMAINING EXPS.). 



Oxygen Consumed, Cubic Centimeters per Hour. 



EXPERIMENTS ON OLIGOCH/ETES. 



The forms used in these experiments were an aquatic earth- 

 worm, Helodrilus tetcedra, one of the megadrilous oligochaetes, 

 and Lumbriculus inconstans, one of the microdrilous oligochaetes. 

 Both of these annelids live in temporary pools in the woods in 

 the dune region of Indiana; the former occurs in the larger pools 

 and also in permanent ponds, while the latter species has never 

 been found in permanent bodies of water. They were collected 

 near Clarke, Indiana. Both species are highly thigmotactic, 

 being found in their natural habitat entwined among the branches 

 of the moss which commonly grows in these pools or lying be- 

 tween layers of dead leaves, their posterior ends usually protruded 

 for respiratory purposes. As the animals are very restless when 

 their bodies are not in contact with objects, an attempt was 

 made to quiet them by placing a small amount of thoroughly 

 washed cotton in the experimental flasks with the worms for 

 some hours preceding the tests. This procedure was entirely 

 successful with Helodrilus; the worms entwined themselves 

 among the cotton fibers and remained perfectly quiet throughout 

 the experiments. It was possible to quiet the majority of the 

 individuals of Lumbriculus in this way also, but a few individuals 

 would always continue to crawl about. No difference, however, 



