DISEASES OP THE DKJESTIVE TRACT .121 



usually pale, showiug areas of congestion (active and passive con- 

 gestion and cloudy swelling). The yolk is only partially absorbed; 

 congestion of the intestines may or may not be present. The 

 kidneys are normal in size, but show congestion and cloudy swelling. 

 The carcass is more or less pale, emaciated and anemic. 



cocciDiAx FORM. — Upou postmortem examination the conditions are 

 found to be similar to those in the bacillary form, except there will 

 be noted more or less congestion of the intestinal mucosa (lining), 

 and ulcers in the intestines, principally the ceca. The ceca appear 

 to contain considerable ingesta. and to be interfered with func- 

 tionally. 



Fig. 52 shows a transverse section through an ulcerated area. 

 In these areas we find cloudy sw^elling, followed by necrosis (retro- 

 gressive changes and death of the cells). The remains of the dead 

 cells form a cheesy mass (caseation necrosis). It will be noted 

 in this drawing that only remnants of a few of the glands normally 

 present are yet intact, the remainder of the mucous membrane and 

 in places the submucous layers are invaded by the germ (protozoon). 

 In Fig. 53 the section B has been magnified 900 times. 



As explained under the cut, all stages of the coccidium tenellum 

 are observed in a mass of dying and disintegrating cells — the re- 

 mains of the diseased mucous lining of the bowel. Repeated exami- 

 nations nave been made of healthy chicks killed for the purpose, 

 and chicks dying from other causes, and thus far no case has shown 

 these conditions. 



In the establishment of the fact that the hen may become chronic- 

 ally infected by the Bacterium pullorum. it also means that she 

 is one of the main sources of infection through the eggs she forms 

 and lays. She may remain chronically infected following a case of 

 white diarrhea w^hile a baby chick or she may acquire the infection 

 after she is mature. This acquisition may be by consuming con- 

 taminated food. The permanent seat of infection appears to be 

 the ovary, which in many instances becomes so greatly involved 

 that the ova are discolored and misshapen, and the ovary presents 

 a decidedly pathological appearance. The ova harbor the disease 

 organism. Ova which develop apparently normal yolks frequently 

 carry the organism. Bacterium pullorum, to the time of full forma- 

 tion of the egg. Infected eggs produce infected chicks and although 

 infected chicks frequently succumb before their embryonic develop- 

 ment is completed or before they pip out of the shell (dead germs), 

 a large percentage of them emerge from the shell apparently sound 

 and well. However, they soon acquire the disease and many of 

 them fall prey to the organism which they carried for a long time 

 in their yolk. These chicks are a constant source of infection to 

 other chicks and to the mature stock. 



A system has been developpfi to test the hens to determine if 

 they are bacillary carriers. This consists of applying the agglu- 

 tination test. 



.Jones in 1912 reports an outbreak of a disease among adult 

 fowls from which the Bacterium pullorum was isolated and to which 

 he attributed the disease. Among 700 hens the mortality w^as 50 

 per cent. There had been no history of bacillary white diarrhea 

 on the farm. A neighbor had been meeting with serious losses, 

 however, and a number of eggs from his fowls were incubated on 

 the farm which had hitherto been free from the disease. Nearly 

 all the chicks that were hatched from these eggs died w'ithin ten days 

 from bacillary white diarrhea. The eggs that failed to hatch were 

 inadvertently fed to adult hens. In these dead hens the Bacterium 



