1888.] 



On the Physiology of the Invert ebrata. 



327 



The above tests clearly prove the entire absence of urea in the 

 secretion under examination. No guanin or calcium phosphate could 

 be detected in the secretion, although the author has found the latter 

 compound as an ingredient in the renal secretions of the Cephalopoda 

 and the Lamellibranchiata (' Edinburgh, Roy. Soc. Proc.,' vol. 14, 

 p. 230). 



From this investigation, the isolation of uric acid proves the 

 renal function of the five pouches of the stomach of the Asteridea. 



II. The Salivary Glands of Sepia officinalis aril Patella vulgata. 



The author has already made a study of the nephridia and 

 the so-called "livers" in both these forms of the Inve^rtebrata (see 

 the memoirs, loc. cit.). Since then he has studied the chemico- 

 physiological reactions of the secretion produced by the salivary 

 glands of the cuttle-fish and the limpet, these organisms representing 

 two important orders of the Mollusca. 



(1.) Sepia officinalis. 



There are two pairs of salivary glands in Sepia officinalis. The 

 posterior pair, which are the largest, lie on either side of the 

 oesophagus. The secretion of the posterior glands is poured into the 

 oesophagus, while the secretion of the smaller anterior pair of glands 

 passes directly into the buccal cavity. A quantity of the secretion 

 was extracted by using several freshly killed cuttle-fishes. It was 

 alkaline to test-papers. A portion of the secretion was added to a 

 small quantity of starch, the starch being converted into glucose 

 sugar in 15 minutes. The presence of glucose was proved by the 

 formation of red cuprous oxide by the action of Fehling's solution. 

 The soluble zymase (ferment) contained in the secretion (which is 

 capable of causing the hydration of starch), was isolated by precipi- 

 tating the secretion with dilute normal phosphoric acid, adding lime- 

 water and then filtering. The precipitate produced was dissolved in 

 distilled water and reprecipitated by alcohol. This precipitate 

 con verts starch into glucose sugar. 



When a drop of the clear secretion is allowed to fall into a beaker 

 containing dilute acetic acid, stringy flakes of mucin are easily 

 obtained. The presence of mucin was confirmed by several well- 

 known tests. 4 



Another portion of the secretion was distilled (with the utmost 

 care) with dilute sulphuric acid, and to the distillate ferric chloride 

 solution was added, which gave a red colour, indicating the presence 

 of sulphocyanates. 



The inorganic constituent, as far as the author could make out, 



