BOTANY. 521 



of the methods of avoiding contagion. He starts with the 

 hypothesis that Schizomycetes, or bacterial organisms, grow 

 in places where there is a certain amount of water; but that 

 they are not so easily disseminated when in water as when 

 in the form of a powder or crust, left after the water has for 

 any reason evaporated. Hence, as regards malarial diseases, 

 the most dangerous districts are not those where standing: 

 water abounds during the whole year, but those where, at 

 some seasons, the water dries up, leaving the organisms in 

 the form of powder or dust, which is easily carried about 

 and dispersed by the wind. Naegeli argues strongly against 

 the prevailing belief that contagious diseases are generally 

 propagated by the drinking-water, but believes, on the other 

 hand, that contagion is generally spread by means of the air. 

 He is also sceptical as to the value of antiseptics and pro- 

 phylactics in general, believing that they frequently do harm 

 by leading to a false sense of security. 



Dr. Koch, whose Observations on the Development of Ba- 

 cillus anthracis were noticed in the Record for 1877, has a 

 second paper on the Method of Examining, Preserving, and 

 Photographing Bacteria. The article is accompanied by 

 three plates, each of which contains eight photographs of 

 bacterial forms. Koch allows thin films of the fluid contain- 

 ing bacteria to dry upon a cover-glass, in order that the 

 bacteria may become fixed. They are then treated with 

 coloring reagents, and allowed to soften, so as to restore 

 their form. They are then permanently mounted and photo- 

 graphed. The coloring matter which Koch found to give 

 the best results was aniline brown. The mo tin tins: fluids 

 used were Canada-balsam and a concentrated solution of 

 acetate of potash. The process employed in photographing 

 is given in considerable detail. The results were satisfac- 

 tory, and in some cases the photographs even show the cilia, 

 which are very difficult to detect in most cases. 



The Development and Action of Bacteria have formed the 

 subject of many papers written by chemists and medical 

 men. Fritz, who has recently contributed so much to the 

 knowledge of the Schizomycetes, which are concerned in the 

 fermentation of different chemical substances, has, during the 

 present year, given an account of a new nostoc-like species 

 which is concerned in the production of butylic alcohol (see 



