78 



PHYSIOLOGICAL CHEMISTRY. 



CELLS OF BACTERIUM TERMO ; from a putrefying 

 infusion. 



able to the- putrefactive change, and it is completely arrested by a heat 

 approaching that of boiling water. 



The process of putrefaction 



FIG. 11. is accomplished by the growth 



and multiplication of a micro- 

 scopic vegetable organism,, 

 somewhat analogous to that 

 causing the alcoholic fermen- 

 tation in saccharine liquids. 

 If any clear solution con- 

 taining animal or vegetable 

 albumenoid matters be ex- 

 posed to the air at a moder- 

 ate temperature, after a short 

 time it becomes turbid. This 

 turbidity is due to the devel- 

 opment of minute vegetable 

 cells, of very simple organi- 

 zation, which rapidly multi- 

 ply in the decomposing li- 

 quid. The cells belong to 

 the genus " Bacterium," so called from their rod-like form ; and the 

 species found in putrefying infusions is known by the name of Bacte- 

 rium termo. The cells are of an oblong form, about 3 mmm. in 

 length by 0.6 mmm. in thickness. They usually appear double, each 

 pair consisting of cells placed end to end. This appearance is due 

 to their multiplication by spontaneous division of the growing cell. 

 After a time the two cells, thus formed out of a single one, separate 

 from each other, and each repeats the process for itself. 



One of the most remarkable characters of bacterium cells is their 

 movement. During a certain period of their development they 

 exhibit an incessant motion, consisting in a conical rotation about 

 their longitudinal axis, by which they are transported in various direc- 

 tions. This motion is often so rapid that it can hardly be followed 

 by the eye ; in other instances it is so slow that its mechanism may be 

 distinguished. The movement and multiplication of the cells go on 

 while putrefaction continues. When all the albumenoid ingredients 

 of the infusion have been decomposed, the liquid again becomes clear, 

 and the bacterium cells subside to the bottom in a quiescent layer. 

 But a small portion of this layer will readily excite putrefaction in 

 another albuminous liquid. 



As the bacterium cells effect the decomposition of albumenoid matters 

 by means of their vegetative activity, putrefaction is limited by the 

 same conditions. Bacteria belong to the group of colorless crypto- 

 gamic plants. Like other plants of this kind, they assimilate organic 

 substances ready formed, at the same time absorbing oxygen and ex- 

 haling carbonic acid, after the manner of animals. 



