418 MILK 



inches long and 6| high. The top is covered by a piece of ground 

 glass over which is placed a square counting plate. The light 

 enters from the front of the box, which is open. The eyes are 

 protected by a shield of wood, 14 by 7 inches, and which is at- 



Fig. 1R5.— A colony counting; apparatus with a cold counting plate for 

 lisp with gehitin plates. (Ayers, in Jour. Amer. Pub. Health Assoc, vol. 

 1, No. 12, December, 1911.) 



t ached to the front of the box. The light should be white. By an 

 additional device cold water can be run into a copper box so "that 

 gelatin plates remain solid. 



The personal equation enters in counting colonies as well 



