Apr. 12, 1924 Development of American Foulhrood 159 



sary for the formation of the stored glycogen and fat, on the basis of the relation 



of their carbon atoms. 



Molec- 

 For- ulor 

 inula weight Equivalent sugar per cent 



Dextrose (unassimilated) CoHi20e = 180 *3. 14 



Glycogen CJi,o05 = 162 ^^°~^^^ X5. 57+5. 57= 6.13 



loU 



Fat (oleic acid)... ..CsHmOj =282 ^^sxiSO^^ '^'^' ^^'^^' ^^'^ ^' ^^ 



Total 14.65 



Since more sugar is used for energy in the production of a molecule of glycogen 

 or of a molecule of fat (SS, p. 77) than is indicated by the actual relation of the 

 carbon atoms, this figure should be somewhat higher, thereby more nearly 

 corresponding with the figure calculated from the weight ratio between in- 

 testine and larva. 



The average concentration of sugar in the food of a larva of the age during 

 which inhibition of bacterial growth takes place is 13.48 per cent (.40) (Table III, 

 fig. 11). The percentage composition of the larva at the different age periods 

 (Table IV, fig. 15) in relation to food composition indicates, however, that the 

 food probably is not assimilated as rapidly as it is ingested by the larva. If 

 this is the case, an increase in the unassimilated sugar in the intestine would 

 occur, as is indicated by the results obtained and the calculated percentage 

 figures. The percentage of glycogen and fat increases slightly by the third day, 

 as a result of the change in the composition of the food and the resulting increase in 

 nursing {S6) . This is accompanied by the appearance of unassimilated sugar in 

 the larva (Table V, fig. 15). There is then a marked increase by the fourth day, 

 when apparently the limit for assimilation is reached, as shown by the constant 

 percentage of glycogen in the larva as a whole between the fourth and fifth days 

 in spite of the increase in weight, until after feeding ceases, when theie is another 

 increase in storage during the next 24 hours (sixth day) . The latter is the result 

 of the consumption of the food remaining in the cell after capping. The amount 

 of unassimilated sugar increases continually, however, until feeding ceases, soon 

 after the larva is sealed in the cell. This fact probably accounts for the slight 

 difference between the percentage of sugar in the food and the calculated per- 

 centage in the intestine, but the correspondence is so striking as to substantiate 

 the assumption. 



Even though these calculations are only approximately accurate, it is known 

 that some such condition must exist, since observations which have been made 

 on the nursing habits of the honeybee (^6), considered in relation to the figures 

 for unassimilated sugar and food composition, give adequate foundation to the 

 conclusion that there is considerably more than enough sugar in the intestine 

 at the time infection occurs, or soon after, to inhibit the growth of the organism 

 causing American foulbrood. 



THE ACTIVE FEEDING STAGE IN THE LIFE HISTORY OF THE LARVA 



The feeding stage of the honeybee larva has been divided into two parts, de- 

 scribed by Lineburg {S6) as the mass feeding period and the progressive feeding 

 period. These two periods are characterized by a difference in the manner of feed- 

 ing and in the amount of time spent by the nurse bees in the process, as well as 

 by the change in chemical composition and character of the food {40) (Table III) , 

 and by the chemical composition of the larvae themselves {4$) .(Table IV). It 

 has been determined, however, that this change in composition of food occurs 



' From Table V. 



' From Table IV, Straus. 



