258 



PHYSIOLOGY OF THE INVERTEBRATA. 



supplied with blood-vessels, many of wMch are intimately con- 

 nected with the folds of the nephridia. There is little doubt 

 that the nitrogenous waste matters are absorbed by the 

 glandular portions of these coiled tubes, and ejected by the 

 contractile parts to the exterior. 



The author * has isolated uric acid from the excretion of 

 the nephridia or segmental organs of Lumhricus terrestris. 

 The contents of these organs do not contain guanin, urea, or 

 calcium phosphate. 



The segmental organs in the Oligochmta are therefore renal 

 in function, eliminating the nitrogenous waste matters con- 

 tained in the blood, in the perivisceral cavity. The largest 

 amount of uric acid was found in the excretion contained in 

 the muscular part of the segmental organ (Fig. 47, outer 

 loop of nephridium). 



The following table is a summary of the constituents of 

 the nephridia or segmental organs of the Annelida : — 



The minute structure of the excretory organs in the Oligo- 

 chmta, especially those of Lunibricvs terrestris, have been 

 worked out by Dr. B. OlaparSde, and detailed in his "Histo- 

 logische Untersuchungen Uber den Eegenwurm," f and also 

 by Prof. C. Gegenbaur. | 



* Proceedings of Royal Society of Edinburgh, vol. 14, p. 233. 

 f Zeitsclirift filr Wissenschaftliche Zoologie, vol. 19. 

 + Ibid,, vol. 4, 



