130 BACTERIAL POISONS. 



(chemotactische Wirkung) to indicate the property of certain 

 chemical agents of attracting leucocytes. 



As has been stated, Buchnee has fouud that the cells of 

 many bacteria coutain pyogenetic proteids. The amount 

 of these substances in the cells varies with the kind of 

 germ, and some species (the bacillus prodigiosus, for in- 

 stance) seem to contain no such bodies. The bacillus pyo- 

 cyaneus contains a large quantity of the proteid, and is 

 suitable for lecture demonstration. The germs are taken 

 from potato cultures and rubbed up with water. Then 

 they are treated with about fifty volumes of a 0.5 per cent, 

 solution of caustic potash. Tliis forms in the cold a muci- 

 laginous mass which dissolves at the temperature of the 

 water-batb. After being heated for some hours the fluid 

 is filtered through a number of small filters ; the first por- 

 tions should be refiltered. The filtrate is a greenish fluid 

 (pyocyanin) which by the careful addition of acetic or 

 hydrochloric acid (an excess is to be avoided) forms a 

 voluminous precipitate (pyocyaneus proteid). This pre- 

 cipitate should be collected on a filter, washed with water, 

 then suspended in water and a few drops of a soda solution 

 added, when a dark-brown fluid, with a tendency to gela- 

 tinize in the cold, containing about 10 per cent, of the pro- 

 teid, is obtained. 



13.254 grammes of the moist bacteria yield 1.44 gramme 

 of dry bacterial substance, and this alter the treatment 

 given above furnishes 0.2739 gramme of dry proteid = 

 19.3 per cent. This proteid leaves 11.52 per cent, of ash, 

 which contains phosphoric acid, but consists principally of 

 sodium chloride. 



Much smaller amounts of proteid were obtained from 

 other germs, but the Ebei-th germ, bacillus subtilis, lactic 

 acid bacillus, red bacillus from potato, and staphylococcus 

 pyogenes aureus furnished considerable quantities. 



The chemotactic properties of these proteids were tested 

 in the following manner : The dissolved proteid was placed 

 in a spindle-shaped glass tube, and the tubes, sterilized by 

 prolonged boiling, were introduced under the skin on the 



