46 RELATIONSHIPS OF THE COCCACE^E 



same culture will show wide variations. For instance, 

 streptococci occur singly, in pairs, chains, and small 

 masses; but the most frequent arrangement, and that 

 observed under the most favorable conditions (liquid 

 media), is in chains. Again, sarcinae occur singly, in 

 pairs, and in small masses, as well as in packets, yet the 

 typical form is the sarcina-packet. Cocci grown on 

 Nahrstoff regularly occur in plates, and usually cap- 

 sulated ones. 



In a number of preliminary studies we compared the 

 groupings of the same cultures in various media and 

 under various conditions, examining cultures of differ- 

 ent ages, — from nutrient broth, sugar broth, pepton 

 solution, hay infusions, nutrient agar, and gelatin, and 

 acid and alkalin gelatin. Cultures more than two 

 weeks old showed abnormalities, both in the individual 

 cell and in its grouping. With this exception, the differ- 

 ences observed were slight. The only apparent effect of 

 the medium upon grouping was a more distinct develop- 

 ment of chains in liquid cultures. Organisms which 

 appear as long chains in fresh broth may show only 

 short chains, with irregular groups, on solid media. 



As a standard routine method we recorded the group- 

 ing of each culture as shown on the agar streak. The 

 streaks used were never more than three days old, and 

 the grouping was observed after staining lightly with 

 methylene blue and mounting in cedar oil. Too heavy 

 staining may introduce a serious error by making packets 



