PHYSIOLOGY OF THE INVERTEBRATA. 227 



The Nematoscolices. 



Very little is known concerning respiration in the Nemo/- 

 toidea, but the investigations of Dr. G. Bunge * have thrown 

 a certain amount of light upon the subject. He has shown 

 that Ascaris mystax (infesting the intestine of the cat) and 

 Ascaris aeus (from the intestirle of the pike) will live four or 

 five days in media quite free from oxygen. In the ultimate 

 respiratory processes of these animals there must be a forma- 

 tion of energetic reducing substances (nascent hydrogen and 

 easily oxidisable organic matter), which unite with one atom 

 of the oxygen-molecule, even to a greater extent than 

 in animals which breathe oxygen. These animals possess 

 no respiratory apparatus, but, d, priori, there may be present 

 in their bodies one or more of the respiratory pigments which 

 retain oxygen within the system ; and this retention of 

 oxygen may be for a considerable time. 



In order to investigate this important question more fully, 

 Bunge employed larger species of Ascaris. The parasite of 

 the horse, Ascaris megalocephala, was found unsuitable, as it 

 only lived for two days after removal from the intestine ; but 

 Ascaris lunibricoicles of the pig lived from five to seven days, 

 and it was therefore used in the investigations. In boiled 

 salt solution it gave off abundance of gas, which was collected 

 over mercury. This gas was completely absorbed by potash, 

 and consisted of pure carbonic anliydride. The quantity of 

 gas obtained in this time was from 5 to 10 cc. per gramme 

 of the animal's body-weight. In three experiments a small 

 measured quantity of oxygen was added to this gas artificially, 

 but there was no diminution in its volume after the ad- 

 mixture ; thus not only hydrogen, but other reducing sub- 

 stances are absent. 



* Zeitschrift fur Physiologische Chemie, vol. 8, p. 48 ; and vol. 14, p. 318. 



