418 . MILK 



inches long and 6J 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- 



185. A colony counting apparatus with a cold counting plate for 

 use with gelatin plates. (Ayers, in Jour. Amer. Pub. Health Assoc., vol. 

 1, No. 12, December, 1911.) 



tached 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 



