316 



Prof. R. W. Atkinson. 



between 35° and 55° C, the paste becomes thinly liquid within 

 a minute and a half, and is perfectly transparent in from five to 

 ten minutes. These results are obtained with a solution containing in 

 500 cub. centims. the soluble matter of 25 grms. of Jcdji ; but it varies 

 with different samples to some extent, and also with the same sample 

 at different periods, the activity becoming less as the sample grows 

 older. If hoji solution of greater strength than that mentioned is em- 

 ployed, the hydrating action upon the maltose takes place so rapidly, 

 that its formation may be overlooked. For a long time, I was under 

 the impression that no maltose was formed, and it was only by using 

 much weaker solutions of hoji, that satisfactory evidence could be 

 obtained of its production. 



The following experiments will, I think, show that the first action 

 of the hoji extract is to split up the starch molecules into maltose and 

 dextrin, and that when the action is continued with a greater quantity 

 of the active agent, the maltose is completely hydrated to dextrose, 

 whilst if samples be taken at intermediate periods, the solution will be 

 found to contain both maltose and dextrose. In this respect, the hoji 

 diastase differs markedly from malt extract, which Brown and Heron 

 have shown to possess no action upon maltose. It resembles, however, 

 the diastatic ferment of the pancreas, which the same observers,* con- 

 firming the work of Musculus and De Mering,f have shown to effect the 

 hydration of the maltose first formed. 



The mode of analysis followed was essentially the same as that 

 described in detail by Brown and Heron. J I will give in full the 

 results of one experiment to illustrate the method. 



A hoji solution was prepared by digesting for a short time 25 grms. 

 of a freshly prepared sample of hoji in about 100 cub. centims. of water. 

 The liquid was then filtered, the residue digested with a fresh quantity 

 of water, and the whole thrown upon the filter and washed, until the 

 filtrate amounted nearly to 500 cub. centims. The solution was then 

 diluted exactly to 500 cub. centims. at 16° C. The filtration occupied 

 three or four hours, even with the assistance of a filter-pump, on 

 account of the slimy nature of the insoluble matter. The solution so 

 made contained in 100 cub. centims. 1*46 grm. of solid matter, calcu- 

 lated from the specific gravity (using the divisor 3'86) ; 1'0125 grm. of 

 glucose, and caused an optical rotation of eight divisions in a 200 millims. 



8 x 0*242 



tube. This gives a specific rotatory power, P~ ^ — - qi^q = ^°'^' 



5 grms. of starch, previously dried at 100° C, were gelatinised with 

 about 75 cub. centims. of water, the paste allowed to cool to 40° C., 7 

 then mixed with 25 cub. centims. of the hoji solution, and left for 



* " Chemical News," xlii, p. 63. 

 f " Bull. Soc. Chim.," xxxi, 105. 



X " Journal of the Chemical Society," 1879, Trans., pp. 600, &c. 



