26i 



is by using an apparatus as shown in figure 4. This apparatus bears 

 a pin, which can be moved over a vertical stand. The pin reaches 

 before the microsaccharimeler, when the stand is placed behind it. 

 To compare tlie mercury levels all is placed on an exactly horizontal 

 table and by removing the apparatus over this table and changmg 

 the angle between the capillary tube and the platter, the two levels 

 can be brought on exactly the same height. 



For using this microsaccharimeter we want (besides diflferent 

 ferment-cultures) : dried and cleaned mercury, paraffin with a melting- 

 point of about 55° C, red sealing-wax of superior quality, some 

 metal spatulas, a platinum spatula in a needle-holder, a number of 

 dropping syringes, some capillary tubes (diameter 1 mm.), some 

 small sterile glass tubes with cotton-wool stops and sterile main-water.') 



^ 2. Preparation of the yeasts. 



For a quantitative analysis with the microsaccharimeter the yeast 

 is to be submitted to a very simple preparation. The yeast quantity, 

 used in this apparatus is in proportion to the quantity of sugar 

 rather large. So the volume of the carbonic acid, developed out of 

 the glycogen present in the yeast can often be very important com- 

 pared to the gas, produced by the fermentation of the sugar. This 

 difficulty is to be prevented ; before bringing the yeast in the appa- 

 ratus, it is made free from glycogen by auto-fermentation. 



The ditferent ferments are the best cultivated in the ordinary 

 culture-tubes on the surface of malt-gelatine. When tubes of a large 

 size are used, one contains enough yeast to do at least six quanti- 

 tative determinations with the microsaccharimeter. With the aid of 

 a sterile platinum spatula the yeast is to be carefully taken from the 

 gelatine-surface and divided in some cc. sterile main water in a glass 

 tube stopped with cotton wool. Then the tubes with the different 

 yeasts are placed in a thermostat at 30° C With the aid of the 

 iodine reaction it can be settled that under these circumstances all 

 the glycogen has disappeared by auto-fermentation after four hours. 



After this preparation the yeast has sunk to the bottom of the 

 tube and the water, standing above, can easily be taken away 

 with a dropping syringe. For this no sterile syringe is wanted, 

 but for each other kind of yeast a new or cleaned one is to be 

 used. 



1) The microsaccharimeter is to I»; had at J. C Th. Marius, Lim., Utrecht 

 the ferment cultures at llie 'Genlralsh'lli' fiii- I'il/.kulturen" at Amsterdam. 



18 

 Proceedings Royal Acad. Amsterdam. Vol. XVIII. 



