54 



veti-:rt nar\- r atiiology. 



granules. The cell membrane is of a protoplasmic nature and 

 is probably formed by condensation of the protoplasmic eel' 

 body, whereas cellulose constitutes the cell niiimbrane of the 

 cells (if hiL;-lier plants. Some species ])ossess orjfans of locomo- 

 tion called flasjella, which are delicate protoplasmic projec- 



4^ w 



Fi,!? :il, — riuy:ellate h;u't*'ria of various torma 



tions (if the cell body or cell membrane. Some bacteria, per- 

 haps all, possess a capsule which appears as a gelatinous sub- 

 stance and is pnibablv derived from the cell membrane. The 

 cell bddy is the essential structure and presides over metabol- 

 ism, reproduction and practically all other functions. Circu- 

 lator\-, ner\'ous and excretory organs are obviously not required 

 in such simple forms of life. The cell membrane protects the 

 cell body. 



(^ 



K — liacteriu. showin;^: capsuh 



liactcria are very small, one eight millionth part of a cubic 

 inch has lieen estimated as the least mass capable of being de- 

 tected with the naked human eye. This space may contain 

 about 2,(11)0,000 bacteria. The dimensions of bacteria are ex- 

 pressed in the term micron which is the unit r)f microscopical 

 measurement. (A micron is 1/2.5,000 of an inch and is desig- 

 naterl ])v the Greek letter 'Aln".) The I'acterium tuberculosis 

 averages about 2.5 microns in length and about .."> microns in 

 width, i. e., 1.000 tuberculosis organisms ]:ilaced end to end 

 would make one inch in length or it A\'Ould take ."iO,000 of these 

 bacteria placed side Ijy side to make a linear inch. Some spher- 



