FUNGOUS DISEASES OF THE HONEYBEE 21 



liancy, and continued drying of the body results in the formation of 

 a mummy of considerable hardness. 



Infection of brood from fungous spores within the digestive or- 

 gans occurs in a manner quite similar to the infection of adult bees 

 (p. 19). Infection of larvae is not limited in its origin strictly to the 

 digestive organs, although this is the usual channel of infection. 

 Spores of two species of Aspergillus, A. pamus and A. fumAgatus^ 

 placed t)n the skin of larvae produced local infection at the point of 

 contact. Germ tubes penetrated the skin and attacked the subcu- 

 taneous tissues in about 15 per cent of the cases in some experiments. 

 This mode of infection occurred in larvae in combs, and in larvae 

 kept on honey or sugar solution in watch crystals. Soon after the 

 skin is penetrated and the mycelium has become well established in 

 the tissues tufts of aerial hyphae and conidiphores appear at the 

 point of infection. (PI. 1, D. ) 



Although these experiments would seem to indicate that direct 

 penetration by ^erm tubes from spores germinating on the surface 

 of larvae is possible, it probably rarely occurs. Even in the experi- 

 ments where masses of spores were placed on the surface of the larvae, 

 germ tubes generally failed to penetrate the skin. 



Results of Inoculation of the Blood of Bees with Spoees of Aspergillus 



In the experiments with caged b^es a few wounded ones were ob- 

 served that appeared to. be attacked in the wound by the fungus. 

 Bees that were inoculated in the tissues or blood were killed more 

 quickly than when spores of pathogenic fungi were taken into the 

 alimentary canal. All of the species of Aspergillus that were found 

 capable of attacking bees through the alimentary canal proved to be 

 pathogenic when introduced into the tissues or blood. Other species 

 that did not attack bees when taken into the digestive organs were 

 found to be capable of attacking bees when inoculations were made 

 by wounding. 



This method of infection could seldom occur in nature on account 



of the constant protection afforded by the body covering. 



- li 



Study of the Physical and Chemical Action of the Fungus on the Infected 



Bees 



The germination of spores of filamentous fungi within the alimen- 

 tary canal of bees and the growth of mycelium here and in the 

 tissues result in disease and death.' It has been stated by Vincens 

 (^7) that "the parasite seems to act by mechanical obstruction of 

 the digestive passages or by paralysis of the muscles of the intestine." 



As a result of the study of freshly prepared mounts, the writer 

 believes that the blocking of the digestive tract is of minor conse^ 

 quence. When the first symptoms appear the quantity of mycelium 

 present within the alimentary canal of infected bees is in most cases 

 so small that it is difficult to understand how it can affect the move- 

 ments of food. Death usually occurs before a sufficient quantity of 

 mycelium has developed to cause congestion within the digestive 

 tract. Frequently, when feeble movements of the appendages or 

 abdominal segments are the only signs of life, only a few scattered 

 hyphae can be found within the contents of the alimentary canal. 



