Apr. 12, 1924 D&velopment of American Foulbvood 163 



until external transformation in form has begun, so that after death the pupa 

 tongue is seen extended and often attached to the upper side wall of the cell in a 

 characteristic manner (fig. 17.) It is possible that in such cases the initial 

 inoculum was smaller than the average, thereby retarding maximum growth 

 of the organism, as was noted in the cultural experiments, and delaying the 

 production of sufficient toxin to kill until this stage of development had been 

 reached. 



While the biochemical relations of the bee larva to the disease are seemingly 

 quite adequate to explain the delay in the time when American, foulbrood is 

 manifest, there is one other consideration which should be mentioned. The 

 abUity of the larva to resist the invasion of the bacteria is a subject on which 

 virtually nothing is known, yet there must be some such ability, as is suggested 

 by the fact that a slight initial inoculum in a colony may not cause the disease 

 to be manifest. At the time when the biochemical conditions are most favorable 

 for the germination and growth of the invading organisms, 

 the larva itself has reached that stage of its development ^X^'^V 



when its internal structure is materially modified by .-^'^BH^fc^. 



histolysis in advance of pupation, and it must follow 

 almost necessarily that its power of resistance is reduced. 

 The extent to which this factor is involved is, for the time 

 being, purely a matter of speculation. 



The variation in the content of reducing sugar of the 

 healthy honeybee larva and the inhibition of the germi- 

 nation and growth of Bacillus larvae by a concentration of 

 over 3 or 4 per cent yield an interesting fact concerning 



the other serious disease of the brood of bees. European ^'°- i^-Decomposed, dried 



*^ down remains of pupa 

 foulbrood makes its attack on the bee larva at an earlier ^^^^ {^qj^ American foul- 

 stage in its development, while the content of reducing brood, showing character- 

 sugars is still high. It must, therefore, be concluded that istic tongue attachment to 

 Bacillus pluton has the ability to grow and rapidly to ^^^^' ''*" "' ™" '^^^"^ 

 produce toxic substances sufficient to kill the larva in a 



medium of much higher reducing-sugar content than has Bacillus larvae, probably 

 as high as 15 per cent. 



THE EFFECTS OF BACTERIAL METABOLISM IN THE LAEVA 



There is little unanimity of opinion concerning the effect of dextrose (glucose) 

 upon nitrogen metabolism by various bacteria. Kendall and Walker (2^) con- 

 cluded that the presence of glucose in the medium delays the production of 

 proteolytic enzym, indicating the "protein-sparing" action of carbohydrates. 

 Fischer {SS) believed that proteolytic enzym is inactivated by glucose, indicated 

 by inhibition of indol formation. Berman and Rettger (6) state that the presence 

 of a carbohydrate in a culture medium may inhibit protein metabolism, depending 

 on the nature of the medium and on the type of the organism as related to hydro- 

 gen-ion concentration. DeBord (SO) believes that some bacteria destroy glucose 

 without marked increase in the hydrogen-ion concentration and that the rate of 

 production of amino nitrogen or ammonia nitrogen, which may be affected by the 

 presence of carbohydrates, indicates different types of metabolism of bacteria. 



The results of the present investigation, although more or less incomplete on 

 this subject, seem to indicate that Bacillus larvae has the abiUty to decompose 

 nitrogenous material in the presence of carbohydrate, since there must be dextrose 

 available until the stored glycogen of the fat body is entirely hydrolyzed. 



Many organisms are unable to attack complex protein unless there is some other 

 source of food present, because, according to Berman and Rettger (6), to be 



