40 THE STORY OF THE BACTERIA 



oidal bacteria. Thus there is a species of mi- 

 crococcus which produces a yellow color when 

 it is growing in masses. This species is called 

 Micrococcus luteus. There is another species 

 of micrococcus which when growing has the 

 peculiarity of a grouping of the micrococci, or 

 cocci, as they are sometimes called, in fours ; 

 this species is called Micrococcus tetragenus. 



Another genus among the spheroidal bac- 

 teria is called Streptococcus, because the little 

 balls tend to cling together and form longer 

 and shorter chains as they grow. Then among 

 the rod-shaped bacteria the most common ge- 

 nus is called Bacillus (plural, bacilli), and some 

 of the species of this genus are among the 

 most common and abundant forms. 



Thus with a temporary and provisional sys- 

 tem of classification, the work of studying 

 and describing the bacteria is steadily going 

 on. And if to see and describe living beings 

 on which no human eye has ever rested before 

 be satisfying, it will be long before the sighs 

 of bacteriological Alexanders are heard in this 

 unseen world, whose very shores have been 

 barely touched by the new explorers. 



