CIRCULATION AND RESPIRATION 



61 



requirements of the recently fed leeches were higher. Hyman 

 (1929) showed that the oxygen uptake of planarians was high 

 shortly after feeding. The oxygen consumption of the leech 

 Erpohdella testacea rose fourfold soon after feeding (Mann, 1958). 

 Von Brand (1946) has reviewed the evidence for the occurrence 



E 

 in 



^ 



20 



15 



iO 



t \ 



\ 



Air-sofurated wafer 



> ■ * T Air-sot. » < Air-sat. -»-*-^Air-sat. 



Fed 



CO treatment 



Time, days 



Fig. 32. Mean oxygen consumption of twenty-two Erpohdella 

 testacea of average weight 45 mg, subjected to various treat- 

 ments as indicated. Lines are drawn to represent twice the 

 standard error above and below each point. After feeding the 

 rate of oxygen uptake rose to a high level, but settled to about 

 7 /Lil/h/leech on the fourth to sixth days. On transfer to water 

 of low oxygen content this rate of oxygen uptake was maintained 

 but after treatment with carbon monoxide the leeches failed 

 to maintain a normal rate of respiration in water of low oxygen 

 content. From Mann, 1958. 



of anaerobiosis in invertebrates and pointed out that when the 

 concentration of the oxygen in the environment falls many animals 

 have an increased consumption of carbohydrate, a greater produc- 

 tion of organic acids and a higher respiratory quotient, indicating 

 that anaerobic fermentation is taking place. He has further 



