9 



organisms, that, finally, it was decided to add still more references of 

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

 as possible, a monographic or comparative study 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 sul)head 2\ hyacinthi is the organism lirst considered, but when- 

 ever comparative studies have made it possible statements are added 

 respecting the Ijehavior of related species. Occasionally mention is 

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

 B. carotovorus, 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 been worked out as thoroughly 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 

 l)est not to give any more time at present to these particular organ- 

 isms, the main features of whose morphology and physiology have, it 

 is believed, been made out correctly. 



GROWTH IX FLUID MEDIA. 



Alkaline Beef Bkoth. 



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 



1 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 21 hours. The 

 mixture was then strained as dry as possiltle 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 thnjugh S. and S. paper, yielding when 

 cold 2,000 c. c. of clear, pale, yelUiw 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 <>f the fluid were titrated against caustic soda, using jihenolphthalein as indi- 

 cator, 10 c. c. requiring 2.5 c. <•. of — XaOH to exactly nentralizi' it. A fermentation 



tube filled at this time (25 c. c of fluid) and aftei-wards inoculated witli PxiriUvs 

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

 fluid was designated 286a. To ol)tain stock 286b, 600 c. c. of this fluid was rendered 



exactly neutral to phenolphthalein by adding 7.5 c. c. of ^NaOH. On eteamnig 



one-half hour a slight precipitate came down. On filtering again the broth ;vas i)er- 

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

 paper. 



