172 EXPEKIMENT STATION EECOKD. 



say that the whites of fresh normal eggs are as a rule sterile. Fermentatioi? 

 tests made of the whites of 105 eggs for B. coli were negative. In noting the 

 kinds of micro-organisms found in the yolks of fresh and incubated eggs it was 

 observed that a large percentage in both cases were staphylococci, usually 

 Staphylococcus alMs or 8. aureus, indicating that there was considerable con- 

 tamination in the examination. Also the occurrence of a large number of 

 members of the sub tills group would suggest the same thing. 



The author reviews the results obtained by earlier investigators, which are 

 not in harmony with those obtained in these tests. He suggests that the 

 methods employed in making previous tests may have been at fault and that 

 it is " highly improbable that normal fresh eggs contain bacteria and molds in 

 such large proportions as various investigators have indicated." It is stated 

 that the developing ova in the ovary of a laying hen are, as a rule, sterile 

 unless the ovary is infected with the organism of bacillary white diarrhea. In 

 200 bacteriological examinations the author was unable to detect bacteria, 

 molds, or other micro-organisms except B. pullorum. It is not thought possible 

 that the blood is a source of infection, and examinations of the oviducts showed 

 them as a rule to be sterile except at or near the cloaca. The views of Horo- 

 witz substantiate those of the author. It is believed that autosterilization of 

 the oviduct is due to the following: (1) Phagocytosis, (2) mechanical action 

 of the walls of the oviduct, and (3) bactericidal action of the secretions. 



The success in preserving eggs with sodium silicate is cited as an indication 

 that sound fresh eggs are as a rule sterile. The fact that many market eggs are 

 decomposed is accounted for by their storage under unfavorable circumstances, 

 i. e., filthy conditions and warm temperature and the fact that bacteria are given 

 an opportunity to enter when the gelatinous coating is removed from the eggs 

 during washing and handling. 



Carbon dioxid in incubation, G. H. Lamson, jr. and H. D. Edmond {Con- 

 nccticut Storrs Sta. Bui. 16 (191^), pp. 219-27S, figs. 13).— The purpose of the 

 investigation reported in this bulletin, which continues studies previously noted 

 (E. S. li., 20, p. 472), was to determine the presence of carbon dioxid in natural 

 incubation and the relative requirements as to ventilation and carbon dioxid 

 during artificial incubation. A specially constructed incubation apparatus 

 that would hatch eggs and at the same time allow for an accurate control of 

 all factors was used. This experimental incubator consisted of four essential 

 parts, the incubator, humidifier, gas meter, and air pump. Two commercial 

 incubators were also used to determine the carbon dioxid in these types, and 

 nests for sitting hens were prepared in such a way as to enable the drawing 

 of samples of air from under the hen. The work extended over five years, 

 nearly 10,000 eggs being used. 



The results of these studies indicated that the chief source of carbon dioxid 

 in incubation is the embi-yo, with the egg shell, hen, nest material, and room' 

 air as minor sources. After the third day the increase of carbon dioxid is 

 proportionate to the increase in weight of the developing embryo. 



The amount of carbon dioxid under sitting hens at the beginning of the 

 period of incubation is much higher than for the room and increases to 50 or 

 60 parts in 10.000, while in the commercial incubators tested it increased to from 

 30 to 50 parts in 10,000. From this it appears that carbon dioxid is not a 

 limiting factor in commercial incubation. However, ventilation is necessary 

 in incubation in order to remove a portion of the respired carbon dioxid and 

 prevent asphyxiation of the embryo. It was found that the normal embryo 

 is able to withstand a wide variation of carbon dioxid during incubation. 

 Little effect was noted on the percentage hatch where the carbon dioxid 



