122 



PATTERNS AND PROBLEMS OF DEVELOPMENT 



total sulphur. He suggested, however, that the oxygen-uptake gradient 

 doubtless includes other oxidation systems than those associated with 

 growth. Okada (1929) and Kawaguti (1934) found a U-shaped gradient 

 of oxygen uptake and CO2 production in the microdrilous oligochete 

 Branchiura. Determinations of CO2 production, of oxidizable substance 

 by a modification of the Manoilov method, and of the temperature of on- 

 set of heat-shortening in the earthworms Pheretima communissima and 

 Allolohophora (Watanabe, 1931) give very similar U-shaped gradients for 

 both species after increase of CO, production following section has disap- 



- -0.005 



Fjq ^g — Gradient of oxidizable substance (heavy line), of CO2 production (medium line), 

 and of heat-shortening temperature (light line) in Allolohophora foetida. CC, cubic centimeters 

 of KMnO,, required for oxidation; C, centigrade temperature; Mgm, milligrams of CO2 per 

 gram per minute; abscissae, body-levels; A, anterior (from Watanabe, 1928). 



peared (Fig. 39). Except for Shearer's conclusion, not based on evidence, 

 that his experimental data were incorrect, there is essential agreement 

 among all these investigators. 



Determinations of CO2 production on N. virens (Parker, 1929) give very 

 different results. He finds rate of CO2 production of anterior and posterior 

 pieces lower than that of middle pieces. Examination of his data, how- 

 ever, shows that rates of the pieces are from 1 2 to 30 per cent lower than 

 that of intact animals and that this difference is due entirely to decrease 

 in the rates of anterior and posterior pieces after section. He finds ante- 

 rior and posterior regions more susceptible than the middle region to cy- 

 anide, and his data on CO2 production suggest that they are also more sus- 



