ANALYSIS OF TISSUES 587 



Three portions of 50 c.c. each are fermented with (a) Saccharomyces 

 marxianus, (^) S. anomalus, (c] S. exigiitts and two portions of 50 c.c. (d) and (e) 

 are fermented with baker's yeast. For the fermentation the acidity of the solu- 

 tion is reduced by adding 2-5 c.c. of N sodium carbonate. 5 c.c. of sterilised 

 yeast water is also added, the mixture sterilised and inoculated with the 

 yeast, stoppered with cotton wool, and kept at 25 for 21-28 days. When the 

 fermentation is complete, 5 c.c. of alumina cream are added, the solution made 

 up to 100 c.c. at 15, filtered and the reduction value of 50 c.c. determined. 

 The amount of maltose is obtained from the difference between the average 

 of (a), (b\ (c) and of (<*), (e). 



(10) 50 c.c. of solution A are distilled with hydrochloric acid for the 

 determination of the amount of pentoses (p. 234). The presence of hexoses 

 does not seriously interfere with the result, but they may be removed by 

 fermentation. 



(n) The amount of glucose and fructose is ascertained by subtracting 

 the values for pentose and maltose. The relative amounts of glucose and 

 fructose are obtained from 



2*205 g + 2*205 f = CuO in gm. reduced per 100 c.c. 1 

 1-48 g - 2*76 f = rotation in i dm. tube in scale divisions. 



(12) A portion of the dried solid from (2) is taken after thorough sampling 

 on a sheet of paper arid dried to constant weight at 1 00 or 1 1 o in vacuo over 

 phosphorus pentoxide. Heating for 24 hours, sometimes longer, is neces- 

 sary. 



(13) The dry material if necessary, previously extracted with 20 c.c. of 

 water for 24 hours, filtered and washed to remove gums, etc. is gelatinised 

 with 200 c.c. of water in a beaker which is heated in a water- bath at 100 for 

 half an hour. 



The solution is cooled to 38, 0*1 gm. of taka-diastase and 2 c.c. of toluene 

 are added and the mixture kept at 38 for 24 hours. The hydrolysis of the 

 starch into glucose and maltose is then complete. The mixture is heated to 

 boiling and the clear solution above the solid material filtered into a 500 c.c. 

 measuring flask, the solid being washed several times with water and the 

 washings collected in the flask until the volume is about 47 5 c.c. Tannins, etc , 

 are precipitated from the solution by adding basic lead acetate, the amount 

 required being from 5-25 c.c. Excess should be avoided, tests being made 

 to ascertain when sufficient has been added. The solution is made up to 500 

 c.c. and filtered. 100 c.c. of the filtrate are placed in a no c.c. measuring 

 flask and the excess of lead precipitated by adding solid sodium carbonate. 

 The volume is adjusted to no c.c. and the solution filtered. The rotation 

 of the solution and the reducing value of 50 c.c. are determined. Supposing the 

 reducing value is equal to -4492 gm. CuO and the rotation value is 1*995, 

 the amount is calculated, using Brown, Morris and Millar's data for i gm. 

 of glucose or maltose and the corresponding amount of CuO, from the equa- 

 tions 



2-369 g + 1-362 m = -4492 



4*216 g + 11*008 m = i'995 



whence = 



no 500 







> 

 g. . 



m = -1394 gm. or . I394 x ^ x 2 = I>5344 ^ J 



Starch corresponding to glucose = 0*90 x 1*2045 = 1*0840 

 maltose = i*5334 T i'Q55 = i'4535 



.*. Total starch = 2*5375 gm. in dried material taken. 



1 2*205 g of CuO are reduced by i gm. glucose or i gm. fructose. 



1*48 = rotation in scale divisions of i gm. glucose in 100 c.c. solution. 

 2*76 = ,. ,, ,, ,, ,, i gm. tructose in 100 c.c. solution. 



(Brown and Morris, 1893.) 



