173 



for the same length of time outside the stables. The Petri dish exposures were 

 made at the same time the Hesse tests were made. The average number of colonies 

 grown on the plates exposed inside the stables was 174, and 55 for those exposed 

 on the outside. In almost every case the number of germs obtained by both 

 Hesse's apparatus and Petri dish exposures was greater inside than outside the 

 stables. It was determined that the number of germs per liter of air could not be 

 taken as an index of the sanitary surroundings. The dust caused by the feeding 

 operation, the moving of bedding, currying, etc., have more to do with the number 

 of germs which will be drawn into a Hesse tube or fall upon a Petri dish than has 

 lack of ventilation. A box stall with sides and ceiling lined with matched lumber 

 with noplace for ventilation or the admission of food except a tightly closing door 

 showed the fewest germs. The air became so foul in twenty-four to thirty hours 

 that acute catarrh developed in the three different horses confined in it during the 

 experiment. 



A description of eighteen forms studied in detail is herewith appended : 



