9 



org-anisms, that, finall}^, it was decided to add still more references of 

 this character and to publish it separately, making this bulletin, as far 

 as possil)le, a monographic or comparative stud}^ of the cultural char- 

 acters of the yellow species of Pseudomonas parasitic on plants. This 

 statement will serve to explain the arrangement of the text. Under 

 each subhead /^v. hyacinthi is the organism first considered, but when- 

 ever comparative studies have made it possible statements are added 

 respecting the ])ehavior of related species. Occasionally mention is 

 made of species not closely related, e. g. Bacillus amylovorus^ B. coli^ 

 B. carotovora.^^ and at the end I have noted some other species which 

 belong to this group of bacteria, and which I have here designated The 

 YELLOW Pseudomonas group. 



Some particulars have not })een worked out as thoroughl}^ as could 

 be wished, e. g., (1) the relative nutrient value of nitrogen compounds, 

 (2) the effect of antiseptics and germicides, but on the whole it seems 

 best not to give an}^ more time at present to these particular organ- 

 isms, the main features of whose morpholog}^ and ph3^siology have, it 

 is believed, been made out correctly. 



GROWTH IN FLUID MEDLA.. 

 Alkaline Beef Broth. 



In test tubes of Weber's resistant glass, containing 10 c. c. of 1:2 

 alkaline beef broth ^ the fluid always showed a feeble clouding in 48 

 hours when inoculated with a 2 mm. loop from a fresh fluid culture of 

 Ps. hyacinthi and kept at 23° C, or thereabouts. Also, when the 

 tubes were inoculated with a much smaller number of germs, viz, as 

 few as could be transferred from a fluid culture on the extreme tip of 

 a platinum needle, the clouding always followed, being a little delayed 



^This beef broth (stock 286b) was made as follows: Into a large beaker of Jena 



glass I put 1,100 grams of finely minced lean beef, covered it with 1,500 c. c. of distilled 



water (from a tin-lined copper tank), and set into the ice chest for 24 hours. The 



mixture was then strained as dry as possible through a clean towel which had been 



thoroughly washed in distilled water before using, an additional 800 c. c. of distilled 



water having been added previous to the straining. The result was 2,350 c. c. of red 



acid fluid. This was put into the steamer, warmed up to 100° C, and left at that 



temperature 45 minutes. It was then filtered through S. and S. paper, yielding when 



cold 2,000 c. c. of clear, pale, yellow fluid. This was then made up to 2,200 c. c. by 



adding distilled water. After thorough mixture of the broth and water by pouring, 



samples of the fluid were titrated against caustic soda, using phenolphthalein as indi- 



N 

 cator, 10 c. c. requiring 2.5 c. c. of — NaOH to exactly neutralize it. A fermentation 



tube filled at this time (25 c. c. of fluid) and afterwards inoculated with BacUlus 

 cloacic yielded 2 to 3 c. c. of gas, indicating the presence of muscle sugar. This acid 

 fluid was designated 286a. To obtain stock 286b, 600 c. c. of this fluid was rendered 



exactly n(Mitral to plienolphtlialciii by adding 7.5 c. c. of —NaOH. On steaming 



one-half liour a slight precipitate came down. On filtering again the broth was per- 

 fectly clear and remained so. It gave a strong blue reaction with neutral litmus 

 paper. 



