ACTION ON LEAD ACETATE. 



81 



deposit fonned was only iil)out one-half the bulk of tlio deposit in (lie 

 pejjtone-niannite tubes. It was of a drab color, eorrespondinj;- v(>ry 

 elosely to Ridgvvay's Ecru Drab, or a little darker than Saccai-do's 

 AvellantHis, No. 7, Talde I, when viewed by reflected li«>ht. The reac- 

 tion of the contents of the tubes was slightly alkaline to litmus at the 

 close of the experiment. The peptone-dextrose tubes began to dear 

 in from ten to twelve weeks after inocula- 

 tion, and m twenty weeks were entirely 

 clear. A large part of the sediment clung 

 to the back of the upright part of the tube 

 instead of settling completely, as in the 

 other inoculated tubes. The color of the 

 deposit was also drab, corresponding very 

 closely to Kidgway's Ecru Drab, No. 21, 

 Plate III, or a little darker than Saccardo's 

 Avellaneus, No. 7, Table 1, when seen by 

 reflected light. The reaction of the con- 

 tents of the tube at the close of the experi- 

 ment was slightly acid to litnuis. The cane 

 sugar, milk sugar, and glycerin tubes 

 cleared in from one to six weeks. The 

 o-lvcerin tube cleared first, then the milk- 

 sugar tube, and lastly the cane-sugar tu))es. 

 The deposit was heaviest — about -i nnn. 

 deep— in the cane-sugar tubes, about 2 mm. 

 deep in the milk-sugar tubes, and only 1 

 mm. deep in the glycerin tube. The color 

 of the deposit was the same as in the other 

 cases, viz, Ridgway's Ecru Drab, No. 21, Plate III, or a little darker 

 than Saccardo's Avellaneus, No. 7, Table I. Each inoculated tube 

 gave an acid reaction with litmus at the close of the experiment. No 

 gas formed in any of the tubes. It is therefore apparent that the 

 calla-rot organism is not capable of splitting up mannite, maltose, 

 dextrose, cane sugar, milk sugar, or gh^cerin so that a gas will form. 



Fig. 6.— Fermentation tube ten 

 days after inoculating with the 

 callii organism. 



ACTION ON LEAD ACETATE. 



Slant tubes of lactose agar, colored with litmus, were inoculated 

 with the calla-rot organism, and at the same time slips of filter paper 

 saturated with lead acetate were introduced into the tubes. These 

 paper strips were held at one end by a cotton plug, so that they did. 

 not come into contact with the medium. In twenty-four hours the 

 color began to fade from the litmus-lactose agar, and in three days 

 the agar was practicall}" colorless, except a small area near the top, 

 which was still slightly tinged. At the same time the lead acetate 

 paper began to blacken around the edges. Twenty -four hours later 

 the margins of the paper strips were still darker and the discoloration 



