84 • ROYAL SOCIETY OF CANADA 



iSection Cutting. — Sections were cut with a good microtome, trans- 

 ferred to warm water and then floated on to cover glasses. These pre- 

 parations were placed in a thermostat at 37° C. until all water had eva- 

 porated. 



Stainiîig, etc. — The paraffin was dissolved in xylol; the sections were 

 then passed through graded alcohols and stained by various methods. 

 The method which gave the best results was the ordinary method of 

 Gram, counter staining with eosin. This gave beautiful preparations, 

 the lactic acid bacteria, yeasts and torulse being well demonstrated, and 

 I should like to call attention to this method as a means of differentiat- 

 ing certain classes of micro-organisms in cheese. Bacteria of the colon 

 type decolorise by this method, but may be stained by using Bismarck 

 brown as a contrast stain. Such preparations whilst useful for study 

 purposes were of no use for photographical use as the cheese or curd sub- 

 stance accepted the brown stain too deeply. By following Gram's 

 method but using amyl alcohol for decolorising and dehydrating all 

 bacteria were stained. Leucocytes in the cheese are often very numerous 

 and as usual were beautifully stained by Gram's method. 



The sections were always cleared in oil of cloves, and mounted in 

 Canada balsam. 



Samples of the curd at various stages of manufacture were taken, as 

 well as of cheese taken from the presses, and small pieces were placed in 

 95^ alcohol, imbedded in paraffin, sectioned and stained according to 

 the methods already given. In order to intelligently follow the result-^ 

 of this work, a few explanatory notes are necessary as to the method of 

 manufacture of Cheddar cheese. The milk is heated to 86°r (30°C) 

 and when the desired acidity in the milk is obtained, which is usually 

 done by adding 0.5'^ of a culture of a lactic acid bacillus, enough ren- 

 net is added to coagulate the milk, nt to cut, in 15 to ^0 minutes. This 

 point is referred to as "cutting time." The curd immediately it is cut 

 i.- stirred by means of agitators for 10 to 15 minutes and then the vat is 

 carefully heated to the cooking temperature of about 98° to 99° F (37'" 

 to S8° C) in one and one half hours from the time of adding the rennet. 

 This point is referred to as " When cooking temperature was reached."' 

 As soon as the acidity of the -whey reaches 0.17 to 0." the whey is either 

 run off or else the curd is dipped out and removed to a special rack. 

 This point is termed " At dipping." The curd is then stirred, piled 

 about 8 inclies high and allowed to mat together. When it is well 

 matted together the piece is cut into strips six to eight inches wide and 

 turned upside down, and in about 15 mmutes time it is again turned and 

 piled two deep. This turning and piling is continued every fifteen min- 

 utes until the curd is ready to mill, which the cheese maker judges by 



