136 



Disease of Bees. 



[JUNE, 



but I of c. Very occasional grains of other species are always 

 met with in addition. These facts demonstrate that the bees 

 have a partiality for a particular species, but do not confine their 

 attention solely to it. A healthy bee out on a foraging expedition 

 confines itself to a single type of plant. 



The contents of the pollen grains were found for the most 

 part to be partially digested and in many cases only the empty 

 coats were remaining. They are but little crushed or distorted 

 and their species could probably be identified if necessary. 



I have not seen a single diseased bee carrying pollen in the 

 " pollen basket " situated on the posterior legs. What pollen 

 they collect they apparently eat. 



The yellow amorphous material (c in Fig C) is another constant 

 feature ; thus in forty-seven diseased bees from Thorley, specially 

 examined for this substance, all contained an abundance of it ; 

 in twenty-one bees from Shanklin, all except two contained the 

 substance, and in about a dozen bees from Great Whitcombe it 

 was found to be present in all of them. The nature of this 

 .substance from an examination made for me by Professor 

 T. B. Wood, M.A., of Caius College,. leaves but little doubt 

 that it is ordinary beeswax. In my own tests I found it to 

 be unaffected by water, alcohol, osmic acid, or strong acetic 

 acid. With strong sulphuric acid it rapidly turns a dirty green 

 colour, while with nitric acid it rapidly loses its bright yellow 

 colour and becomes greyish. It is soluble in both chloroform 

 and xylol and partly soluble in potassium hydroxide, and 

 when warmed on a glass plate it rapidly melts. In many cases 

 this material seems to have been formed around a pollen grain, 

 or several of the latter as a nucleus, and, after treatment with 

 caustic potash, they are often visible in the centre of the yellow 

 material. In a very few instances a few stellate plant hairs 

 (very like those of Deutzia gracilis) have been found among the 

 contents of the colon, and in two cases they were noticed to 

 serve, as it were, as a nucleus for this substance to be deposited 

 around. 



The obstruction in the digestive system is situated in the 

 rectum itself, about the point x in Fig B. The muscles of the 

 rectum are tightly contracted and no pollen is able to pass 

 through. 



Smears made from the contents of the colon and fixed by heat 



