236 THE AMEEICAN MONTHLY [October, 



a " safe " light until the image has well appeared and shows well 

 through the back, which if all has gone right should be in two or three 

 minutes ; the plate is then washed in two or three changes of water and 

 fixed in thiosulphate of soda or " hypo," as it is more commonly called. 



The " hypo" dissolves out of the film all the unchanged salts of 

 silver, but leaves untouched that part that has been blackened or re- 

 duced by the developer. 



The fixing bath should be allowed to act for fully ten minutes, in 

 order to completely remove all unreduced silver from the film, and it 

 then must be subjected to a prolonged washing in running water till all 

 traces of the salt is removed, or the negative will inevitably deteriorate. 



The negative is now allowed to dry spontaneously, and if valuable 

 may be varnished to preserve it ; but this is not absolutely necessary, 

 as it does not improve the printing qualities, and with ordinary care 

 the plate does not suffer any injury in printing. 



Printing may be effected on ordinary sensitized albumen paper by 

 daylight, but if opportunities for printing only occur at night, bromide 

 paper may be used. 



The surface of bromide paper resembles that of the plates used for 

 the negatives, and good contact prints may be made by gas or lamp- 

 light, which must be developed in exactly the same way as the plates, 

 viz., with ferrous oxalate or quinol, pyrogallol as a rule not being so 

 well adapted for paper development. 



Lantern transparencies can be produced in exactly the same way on 

 gelatin-coated plates, either by contact printing or the use of camera 

 and lens. 



BACTERIOLOGY. 



Bacteria found in Influenza. — Secretions from the respiratory 

 passages and juices from the various organs from cases of influenza 

 were used by Dr. V. Babes as intravenous and subcutaneous injections 

 in guinea-pigs and rabbits. The animals were also infected by rub- 

 bing their nasal mucosa with the tainted discharge. Many of the an- 

 imals succumbed to the poison, but on the other hand many survived, 

 an inflammatory swelling only being developed at the place of inocula- 

 tion. From the organs of the animals which died cultivations were 

 made on agar, gelatin, and potato, and several forms of bacteria devel- 

 oped. Among these were Staphylococcus pyogenes aureus and albus, 

 and also a Staphylococcus from 0.8 to i .o,a broad, which did not liquefy 

 gelatin, and was not pathogenic. Of the bacilli, two forms distin- 

 tinguished as B I and B // are specially noted. The colonies of bacil- 

 lus i are distinguished by being perfectly transparent and colorless. 

 The individual elements which are extremely small, from 0.2 to 0.4/1 

 thick, form small chains or threads. They are only faintly stained by 

 anilin pigments, and not at all by Gram's method. They are quite 

 motionless. Bacterium ii was found to stain well. The primitive 

 elements, usually in pairs, are about 0.5/7. broad, with pointed ends. 

 Transverse striations could be detected. These bacilli did not grow 

 on gelatin, but throve on potato. They were found to be pathogenic 

 to mice and guinea-pigs, their chief efl'ect being exerted in the lungs. 



