ST&;<)MYI.\ / l>r/ 17.1 AM) ITS RELATION TO YELLOW FEVER 543 



sharply defined pictures, in which the black margin corresponds to the 

 contour of the object. The illuminated portion is surrounded by a fine 

 dark /.one, this in turn by alternate bright and dark zones, in which the 

 illumination rapidly decreases. 



With a suitable apparatus both stained and unstained bacteriological 

 specimens can be examined. 



Variation in Susceptibility of Guinea-pigs to Diphtheria Toxin. 



Smith has recently shown that a small percentage of guinea-pigs shows 

 a marked resistance to the poisonous effect of diphtheria toxin. This 

 refractory condition is inherited from the mother. This fact has to be 

 considered in the testing of toxin and antitoxin. 



Diplobacillus of Morax-Axenfeld, 



This organism appears to be the exciting agent of a fairly frequent 

 and peculiar infectious disease affecting only, so far as known, the 

 human conjunctiva. The organism was discovered independently by 

 Morax and Axenfeld in 1896. It is not pathogenic for animals. The 

 usual clinical picture is that of a "blepharoconjunctivitis." The sub- 

 jective symptoms are relatively slight. 



Examination of the conjunctival secretion shows the characteristic 

 bacilli. These are arranged mostly in twos, though long and short chains 

 are also found. The bacilli average 2/u long and \fJ. wide, though smaller 

 diplobacilli are often seen, probably younger forms. The ends of the 

 organisms are slightly rounded, and usually of the same thickness as the 

 rest of the cell. The line of demarcation between the individuals is 

 distinct. The bacilli are not stained by Grain's method and have no 

 distinct capsules. The organism grows only at near the body temperature 

 and best on solidified blood serum or serum agar. The medium must 

 be alkaline. 



Bacteria in Ice. 



Water when it turns to ice destroys a considerable percentage of the 

 vegetative forms of bacteria. Spores are not, as a rule, injured. Ice 

 six months or more after freezing contains very few bacteria even when 

 made from polluted water. Not more than 10 per cent, of typhoid 

 bacilli survive freezing. At the end of one week not more than 1 per 

 cent, remain alive. Not one in one thousand survive for one month, and 

 none for more than six months. The colon group of bacilli are a little 

 more hardy than the typhoid bacilli. 



Stegomyia Fasciata and its Relation to Yellow Fever. 1 



The experiments made by Reed, Carroll, and Agramonte make it 

 certain that yellow fever was transmitted by a mosquito (Stegomyia 



1 This account IB taken from the article by Agramonte in Laboratory Work with Mosquitoes, by 

 Berkeley. 



