436 



Mr. T. Goodey. The Excystation of [Feb. 28, 



completely digested by diastase and in some cases by ptyalin. It is therefore 

 highly probable that this endocyst material is of a carbohydrate nature. 

 This raises a point of considerable interest, for the endocyst was digested by 

 the heated as well as by the unheated diastase, thus showing that the seat of 

 the enzymic activity was not confined to any cytase which might have been 

 present in the diastase as an impurity.* 



Diastase is generally considered to act only upon starch and glycogen. 

 The substance under consideration is certainly neither starch nor glycogen 

 and yet it is digested by diastase. In this respect also it differs from 

 paramylum, which is untouched by diastase. 



Paraglycogen is soluble in hot water, and the solution is hydrolysed into 

 dextrin and a trace of reducing sugar, thus differing from glycogen, which 

 yields dextrin and plenty of reducing sugar when hydrolysed with the 

 salivary ferment. It is because of this difference that Biitschlif called it 

 paraglycogen. 



Since diastase digested the endocyst, chemical tests for carbohydrates were 

 sought. Attempts were made to obtain an osazone from the liquid in which 

 Colpoda had been caused to excyst, after proper treatment with sodium 

 acetate and phenyl-hydrazine hydrochloride solutions, but only negative 

 results were obtained. It was concluded that the carbohydrate produced by 

 the digestion of the endocyst was present in far too small a quantity to be 

 detected by this method. 



Colour Reactions for the Detection of Carbohydrates. — A method^ was found 

 by which dextrose, lactose, saccharose, starch, and cellulose, when heated up 

 with strong hydrochloric acid and scatole, yield a violet coloration, the 

 reaction still showing at a dilution of 1 : 300,000. Fifteen grains of scatole 

 were obtained, and tests were made with dextrose, starch, lactose, saccharose, 

 cellulose, and hay-infusion, by heating them in test-tubes with strong 

 hydrochloric acid and small quantities of scatole. In all cases a violet 

 coloration of the liquid resulted, even when dextrose diluted 1 : 300,000 was 

 used. Hay-infusion could not, therefore, be used for the excystation of 

 Colpoda from cysts in this experiment. 



Cultures were therefore made in distilled water containing O^Ol-per-cent. 

 caustic soda, this being the percentage of alkali in the hay-infusion commonly 



* Occasionally one or two fibres of cellulose from the filter paper on which the cysts 

 had been collected were introduced into the hanging drops along with the cysts. These 

 fibres never showed signs of corrosion or solution, thus showing the freedom of the 

 diastase from cytase. 



t Loc. ext., p. 1484. 



% 'Jour. Chem. Soc.,' 1907, vol. 92, Pt. 2, Abst., p. 308 ("Colour Eeactions of 

 Carbohydrates with Indole and Scatole " ). 



