PREVENTION 497 



ditions, including cleanliness, ventilation and the temperature 

 of the poultry houses, must be considered. Undoubtedly there 

 is much to be learned in connection with the proper sanitary 

 care of poultry. In addition to the general sanitary methods, 

 the following rules should be ob.served. 



1. Fowls which have an exudate on any of the mucous 

 membranes of the head or which have come from flocks in 

 which such a disease exists or has recently existed, should not 

 be placed among healthy poultry. 



2. If the disease appears in one or more fowls of a flock 

 they should be immediately separated from the well ones. If 



Fig. 1 20. Photographs of transections of fowl's head. 

 I, 2 and 3. Sections from a normal head. 



4, 5 and 6. Sections from approximately corresponding levels from 

 the heads of fowls suffering with diphtheria. 



1. Cross-section of a chicken's head just posterior to the nasal 

 openings, a Nasal passage, d turbinated bone, r portion of the wall of 

 the false nostril, d sub-orbital sinus, e palate. 



2. Cross-section of a chicken's head midway between the nasal 

 openings and the eyes, d Sub-orbital sinus, d' superior portion of the 

 sub-orbital sinus, which connects with d posterior to the lachrymal 

 duct,/ lachrymal duct opening into the mouth through the cleft palate. 



3. Cross section of a chicken's head on a level with the anterior 

 part of the eyes, d Sub-orbital sinus and the duct connecting it with 

 the nares. 



4. Cross-section of a chicken's head just posterior to the nasal 

 openings, showing the swollen condition of the nasal mucosa in the first 

 stage of the disease. The nasal passages are nearly occluded. /> Tur- 

 binated bone with swollen mucosa, d' sub-orbital sinus containing a 

 small amount of exudate. 



5. Cross-section of a chicken's head midway between the nasal 

 openings and the eyes, showing extensive exudate in the left sub- 

 orbital sinus d and nasal passage extending into the cleft palate ;;/. 

 The exudate is crowding upon the turbinated bones and nasal septum. 



6. Cross-section of a chicken's head through the eyes, showing 

 exudate in the conjunctival sac, inflammatory thickening of the eyelids 

 andmembrana uictilans, and ulcerated cornea, a' Kyelid, // membrana 

 nictitans, i exudate in the conjunctival sac, /• ulcerated cornea, / eye. 



All sections are magnified two diameters. 



