348 



Dr. P. F. Frankland and Mr. J. J. Fox. [June 20, 



Appearance on Potatoes. — Forms a dirty-white, shining growth 

 which extends over almost the whole surface of the potato. 



Appearance in Gelatine-Plate Cultivations. — To the naked eye the 

 colonies are very insignificant, appearing as small white dots ; later on 

 when liquefaction commences, clear liquid circles form round the 

 small centres, the circles gradually increase in diameter until the 

 whole plate may become involved. 



Under a low power ( X 100) the depth-colonies in which neither 

 softening nor liquefaction of the gelatine has commenced, are seen 

 to be smooth-rimmed disks with finely granular contents (see fig. 3), 

 whilst those around which liquefaction has taken place exhibit a dark 

 central mass surrounded by very finely granular matter, the periphery 

 having a delicate hair-like appearance (see fig. 4). The same dif- 

 ferences in the rate of liquefaction are observable as in the case of the 

 gelatine-tube cultivations referred to above. 



In none of the cultivations were any spores discoverable. 



Fig. 3. 



Fermentation of Mannitol. 



The fermentations were carried out in flasks of about 2-J litres 

 capacity; the mannitol was employed in a 3 per cent, solution, 

 2000 c.c. of solution being placed in each flask. The solution was 

 prepared as follows : — 



60 grams of pure mannitol, 2 grams of dry peptone, and 30 grams 

 of precipitated calcium carbonate were placed in the large flask ; 

 200 c.c. of a salt solution* containing the necessary mineral ingre- 

 dients for the growth of micro-organisms, were diluted to 2000 c.c. 

 with distilled water and then added to the flask containing the 

 mannitol, &c. The flask was then famished with a plug of sterile 

 cotton-wool, and the whole steam-sterilised for upwards of one hour 

 on three to four successive days. 



* This salt solution contained— 



Potassium phosphate 5 •00 grams ] dissolved in 



Magnesium sulphate (cryst.) 1-00 ,, 15000 c.c. of 



Calcium chloride (fused) *50 J water. 



Fig. 4. 



