1894] MICROSCOPICAL JOURNAL. 3 



LABORATORY STUDIES. 



The first step in examining the yeast sample is the mi- 

 croscopical examination. The Leitz microscope, oc. 2, 

 obj. 6 or the excellent Seibert lenses, oc. 0-3, obj. 3 and 

 6 give good and clear pictures ; any microscope with 

 good lenses, and about 600 diam., magnif., will prove 

 satisfactory. 



It is desirable to have 15-20 glass rods in a rectangu- 

 lar tin box. These can all be flame-sterilized at once; a 

 glass with 1 per cent corrosive sublimate «<olution should 

 be kept at the table for the rods out of use. The clean 

 and sterilized tin box is to be covered with a thick glass 

 plate. It should be remembered that the bottles must be 

 well marked with numbers corresponding to the numbers 

 in the note book. 



The bottles must not be shaked very much when they 

 are taken out of the ice box as the cork might come oft" 

 and the contents be infected from the air. The cork 

 should be lifted cautiously, and a glass rod dipped down 

 to the bottom of the bottle. When it has been taken out 

 again rapidly, the drop hanging at its end is placed on a 

 slide ; a cover is put over it, and we have now a sample 

 ready for microscopic examination. 



Before entering upon the various organisms which 

 might come under observation, it ought to be remem- 

 bered that drawings of everything seen should be put 

 down in the note book. 



The examination of a sample of yeast from the brew- 

 ery will be illustrated by the follow^ing example. 



I. Microscopic analysis. This is the first step. 



The picture might be as in Fig. 1. It is evident that 

 we have here two distinct forms of cells, a shows short 

 rows of round or oval cells apparently in vigorous de- 

 velopment, judging from their many buds; h shows ob- 

 long or rectangular cells, many of which are budding. 

 The latter forms of cells are commonly called "pastorian 



