322 



SCIENCE 



[N. S. Vol. XLII. No. 1079 



test solutions. The test substances used were dex- 

 trose, lactose, saccharose, raffinose, inulin, saliein 

 and mannit. 



The main conclusions reached by the work are: 



1. The power to hemolyze human and goat's 

 blood may be acquired to some extent by animal 

 passage. 



2. Animal passage develops and increases viru- 

 lence of Sir. lacticus. 



3. Virulence develops more rapidly in rabbits 

 than in guinea-pigs. 



4. By animal passage the amount of acid pro- 

 duced in the original strain decreases progres- 

 sively and fermentation of some of the substances 

 is inhibited. 



5. Eaffinose and inulin, which were not fer- 

 mented by the original strains, were fermented 

 to a limited degree after animal passage. 



6. Presence of free oxygen seems to favor the 

 production of acid. Under anaerobic conditions 

 less acid was produced than with free access of 

 oxygen. Under anaerobic conditions fewer sub- 

 stances were fermented than under aerobic con- 

 ditions. 



Bacterial Infection of Fresh Eggs: Dokothy 



W. Caldwell. 



This paper presented the results of a bacterio- 

 logical study of fresh eggs carried on at the Agri- 

 cultural Experiment Station of the Rhode Island 

 State College. The results are, briefly, as follows: 



1. Of 2,510 fresh eggs from 65 hens, examined 

 by the indirect method, 8.8 per cent, showed in- 

 fection in the yolk. 



2. None of 111 whites examined showed infec- 

 tion, whUe the yolks of the same eggs gave a per- 

 centage of infection (4.5) less than the average 

 for the series (8.8). 



3. The percentages of infection obtained for 

 individual hens per year varied between 2.8 and 

 15.0, the average being 8.0 per cent, per year. 

 No hen laid sterile eggs during a whole year. 



4. No correlation was observed between the per- 

 centage of infection for any individual and the 

 degree of fecundity of that individual. 



5. Approximately the same amount of infee 

 tion was found among fertile eggs (6.9 per cent, 

 infected out of 422 eggs examined) as among in 

 fertile (8.9 per cent, infected out of 315 eggs) 



6. The infection of eggs in the degree made ap 

 parent by the present studies seemed to have no 

 unfavorable effect upon their hatchability. 



7. Practically no difference between the per- 

 centages of infection of eggs from pullets and 

 from hens in their second laying year was found. 



8. No definite seasonal variation was observed 

 in the bacterial content of the eggs examined. 



9. No definite conclusions can be drawn from 

 these studies regarding the influence of tempera- 

 ture upon the detection of infection in fresh eggs. 



10. From fifty-seven infected eggs out of 737 

 examined in one of the series, 37 bacterial types 

 were isolated, among which were seven cocci, 

 eleven motile rods, eighteen non-motile rods and 

 one spirillum. 



11. Control plates exposed under the hood in 

 which the examinations were made yielded a va- 

 riety of organisms, largely chromogens. This 

 series, as a whole, did not resemble the series of 

 egg organisms. 



Regarding the source of infection, this study 

 indicated that the penetration of the shell after 

 the egg had been laid, or infections during the 

 passage of the egg through the cloaca, or during 

 fertilization or while the albumen or the shell 

 were being deposited, aie, to say the least, un- 

 common. It seems more likely that infection of 

 fresh eggs is largely due to occasional chance in- 

 fections with harmless organisms taking place 

 within the ovary of the fowl. 



A New Microscopic Test for Pasteurized Milk: 



"W. D. Frost. 



This test differs from a similar one described in 

 1911 by Frost and Ravenel, in the method of ap- 

 plying the stain, the nature of the stain and the 

 principle involved. A few cubic centimeters of 

 milk have mixed with them one fifth as much of 

 a saturated aqueous solution of methylene blue. 

 This colored milk is allowed to stand about 30 

 minutes; it is then centrifuged and the sediment 

 spread on a glass slide. When dry it is ready for 

 examination. 



In raw milk the microscopic field is stained a 

 uniform blue in which appear clear areas which 

 are either fat globules or leucocytes. The poly- 

 morphonuclear cells are irregular in outline, about 

 12 mikrons in diameter and unstained or only 

 slightly tinged. The sediment from milk heated 

 to 60° C. or above presents a very different pic- 

 ture. The polymorphonuclear leucocytes are 

 rounded up and shrunken so that they are only 

 about 8 mikrons in diameter and the nuclei are 

 deeply stained. 



The method requires little more time than it 

 does to make a fat determination and is appar- 

 ently as simple and accurate as the laboratory 

 diagnosis of diphtheria or rabies. 



A. Parker Kitchens, 



Secretary 



