W. COLE ON A PARASITE OF HUMBLE BEES. 95 



are on record of their appearance in great numbers under circum- 

 stances so mysterious as to lend some colour to the popular idea 

 that they had been precipitated from the clouds in a shower of 

 rain. In June, 1867, such an eruption of Mermis nigrescens occurred, 

 "which occasioned much discussion and speculation, and furnished 

 materials for a paper read by Mr. R. T. Lewis before this Society. 

 In that paper (which is printed in " Science Gossip" for 1867) 

 may be found some valuable details as to the minute structure of 

 Mermis, which are interesting from our present point of view, this 

 " hair-worm" being probably the nearest known relative of 

 Sphcerularia. 



The merit of discovering this extraordinary creature belongs to 

 the celebrated insect anatomist Leon Dufour, who described it in 

 the " Annales des Sciences Naturelles" for 1836. He at first 

 supposed it to be a dipterous larva, many of which infest insects ; 

 but on further consideration of its structure he perceived that he 

 had before him a new genus of Entozoa, and he accordingly brought 

 it before the scientific world under the name of Sphcerularia Bombi. 

 In 1838, Von Siebold published a few remarks on the animal, and 

 pointed out the position it should occupy in systems of classification ; 

 but the naturalist who made the first thorough attempt to work out 

 its development and anatomy was Sir John Lubbock, in the " Natural 

 History Review" for 1861. The same Journal for 1864 contains 

 the results of some further investigations made by him ; and in 

 these two memoirs will be found nearly all the information we at 

 present possess oh the subject. I need hardly say how much I am 

 indebted to these admirable papers. 



Finally, I understand Schneider has made some observations on 

 the morphology of Sphcerularia in his work on the Nematodes, and 

 has therein expressed an opinion as to its structure, to which I can 

 more conveniently refer presently, after we have considered the 

 details of its anatomy. 



Nothing is easier than to obtain specimens of the parasite from 

 an infected bee. The insect should be killed by some mode of 

 suffocation, such as being placed in the vapour of sulphurous or 

 hydrocyanic acids, and carefully dissected under water. The 

 Sphcerularia? are not found, as is comm6nly the case with the 

 mature Entozoa, in the interior of the alimentary canal. They lie 

 perfectly free among the viscera in the upper portion of the ab- 

 dominal cavity, and are bathed on all sides with the nutritive fluids 



