606 HORSE, SWINE AND POULTRY DISEASES 



Some very recent experiments have shown that the eggs of 

 virgin pullets reveal a much lower rate -of bacterial infection than 

 eggs from females that have been associated with the male bird. 

 The act of copulation as carried out among fowls always results in 

 the introduction of more or less dirt into the oviduct of the female, 

 thus entailing gradual infection of the egg tube and ovary with 

 microbes found in the soil contaminated with poultry droppings, 

 to say nothing of the transfer from the cock bird's cloaca of path- 

 ogenic micro-organisms derived from his own intestinal tract. It 

 has long been recognized in a general way that infertile eggs did 

 not suffer putrefaction in the incubator, while fertile eggs that did 

 not go on to the development of the embryo were quite prone to 

 become rotten. 



The investigations referred to furnish the exact status of this 

 question. There are infertile eggs other than those from virgin 

 pullets but it is not so much the infertile eggs as the eggs from virgin 

 pullets that are free from infection. And here the poultrymen's 

 judgment and experience placed him on ground which the bac- 

 teriologist has now justified. Knowing from other and extensive 

 investigations that constant breeding from pullets resulted in de- 

 terioration of the stock, poultrymen have taken to using their 

 pullets merely as layers, reserving them for breeding only after 

 the pullet age was passed. Then, as stated above, believing that in- 

 fertile eggs did not spoil as quickly as fertile eggs, they decided 

 that it was best to keep these laying pullets apart from the male 

 bird. These investigations have justified this course and have also 

 demonstrated that immediately upon association with the male 

 bird the females are in danger of infection of the egg tube and egg 

 bag and consequently of the egg itself. Recognizing this possibil- 

 ity that constantly menaces the breeding birds as against the layers, 

 if disease persists among the chicks in spite of cleaning out the intes- 

 tines of the old birds, and spreading lime about the place and 

 cleansing the water supply, and dipping the eggs prior to incuba- 

 tion, and disinfecting the incubators and brooders, the poultryman 

 should look to the breeding stock. It must be remembered that 

 from the moment a hen is mated there arises the possibility of infec- 

 tion of the reproductive organs which may be transmitted to the egg 

 and so to the embryo, causing either death in the shell or of the 

 newly hatched chick. All mated birds must therefore be regarded 

 as potentially infected. 



The experiments of Rettger and Stoneburn at Storrs Agricul- 

 tural Experiment Station in the investigation of Bacterium pul- 

 lorum are conclusive as to the transfer of disease-producing mi- 

 crobes from the ovary of the hen to the egg and thence to the em- 

 bryo, thus causing death of the embryo in the shell or a fatal sep- 

 ticemia of the newly hatched chick. 



APPLICATIONS OF THE MAXIMS TO THE TREATMENT OF DISEASE. 



It must not be imagined that all necessary treatment of disease 

 begins and ends with the employment of the seven maxims which 

 have been enunciated. These fundamental principles have their 



