ANAEROBIC METABOLISM 



205 



of staining methods fat can be demonstrated within the 

 excretory system (Prenant, 1922; von Brand and Wein- 

 land, 1924; Vogel and von Brand, 1933; cf. Fig. 5). Its 

 identification there is a definite proof that its appearance 

 amongst the excreta cannot be due to bacterial contami- 

 nants. 



Fig. 5. Young Fasciola liepatica from body cavity of guinea-pig, 24 

 hours after infection, sliowing the excretion of fat. The fat droplets 

 were stained by means of Sudan III and are represented in the drawing 

 by circles and dots. I, intestine; E, excretory bladder containing fat 

 droplets; P. fat deposited in the parenchyma. (Prom Vogel and von 

 Brand, 1933.) 



The excretion of organic acids by Hirudo medicinalis 

 under anaerobic conditions was studied by Braconnier- 

 Fayemendy (1933). She states that 98 per cent of the 

 excreted acids are volatile and belong to the fatty acid 

 series. Butyric acid was found to be the predominant 

 one. The other acids were not definitely identified. They 



