APPENDIX I. 



FIRMS SUPPLYING APPABATUS, UTENSILS, ETC. 

 (Only the most important apparatus, etc., is mentioned.) 



Seed and plant material : HAAGE and SCHMIDT, Erfurt. 



Pressed yeast : VERSUCHS- UND LEHRBRAUEKEI zu Berlin, See- und Torf str.- 

 Ecke. Also pure yeast cultures in test tubes, price 10 mk. In 

 many cases it is sufficient to purify the yeast oneself. Yeast from 

 a brewery is distributed in distilled water which has been sterilised 

 by boiling. When the larger particles floating in the fluid have 

 settled, we pour off the fluid in which the yeast cells are suspended, 

 and put it in a cool place. When the bulk of the yeast has settled, 

 we pour off the turbid fluid, distribute the sediment once more in 

 water, and decant as before, proceeding in this way say four times 

 more. The purified yeast is now again distributed in water ; some 

 is allowed to settle, and we then remove by means of a pipette a 

 known volume of the yeast-containing fluid. Instead of the water 

 last used, we may, under some circumstances, employ a certain 

 quantity of a food solution (Pasteur's food solution, beer wort, etc.) 

 appropriate for yeast cultures. If it is required to provide various 

 portions of food solution with precisely the same quantities of yeast, 

 it is well to proceed as follows: Water or food solution is supplied 

 with purified yeast, as above, and then a quantity of the fluid is 

 transferred to a further quantity of water or food solution, the 

 final samples being removed by means of a pipette from this fluid, 

 which is kept well shaken. In many cases it is necessary first to 

 sterilise the water or food solution, in which yeast is to be dis- 

 tributed, by boiling in a flask plugged with cotton wool. 



Chemicals of all kinds are to be obtained from the chemical works of 

 MERCK, Darmstadt, 



Pigments for microscopy : Dr. G. GRUBL.ER, Bayrische Strasse, Leipzig. 



Filter paper, ordinary and Swedish : Dr. H. GEISSLKR NACHF. F. MULLER, 

 Bonn. 



Corks, indiarubber bungs, indiarubber tubing, etc., are to be obtained 

 from the rubber works of WAI.LACH, Cassel. Rubber goods should 

 be kept in a large closed glass cylinder, in which is a small glass 

 half filled with turpentine. Preserved in this way, they do not 

 become brittle and full of cracks. Bubber articles which have got 

 hard can be rendered serviceable again by exposure for some time 

 to the influence of chloroform vapour. They may be placed for 

 the purpose in a closed glass cylinder, together with a glass half 

 filled with chloroform. 



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