212 T. CHARTERS WHITE ON EMITS A VLVSCJE. 



then may be recognised by a zone of white deposit surrounding the 

 fly like a halo — the fly maintains its living attitude, and will be 

 found attached solely by the lips of its proboscis. Its legs are not 

 crossed under it as is the case with all dead insects, but distended, 

 as in the live state. Examining the fly now externally, you will find 

 the hairs covered with minute white globules. These are the spores 

 of the fungus, and are scattered also round the fly for some 

 distance, in a very curious manner ; in some cases almost as if they 

 had been squirted out of regular points of the body. The abdo- 

 minal rings are separated by about their own breadth from each other, 

 while they seem bursting from over-distension. The thorax and head 

 do not seem so much affected as the abdomen. On opening the fly 

 in a little glycerine and water, the cause of this over-distension is 

 soon discovered by the appearance of a dense mass of mycelium 

 threads, that emerge as soon as an opening is made in the abdomen. 

 It is not an easy thing to make a tidy dissection of a fly in this 

 state, for it becomes so dry and brittle under the influence of this 

 disease, that it breaks up on the slightest force being applied. A 

 small portion that I was enabled to procure I have stained with 

 carmine, and placed under my microscope for inspection this evening. 



With these few particulars relative to the external appearances 

 presented in these diseases, it will, perhaps, be as "well to enquire 

 into the origin of it, and here in the absence of all particulars 

 relative to the life history of the fungus, we are placed face to face 

 with a difficulty that needs to be overcome by further investigation. 

 We are aware that fungoid diseases manifestly affect many insects, 

 as instanced in the muscardine, so fatal to silkworms. The Botrytis 

 bassiana, principally concerned in the production of this disease, is 

 supposed to enter through the breathing pores, the sporules being 

 drawn into the tracheal tubes of the silkworm, where they develop 

 so rapidly that the tubes become blocked up ; now, in the fly, the 

 tracheal tubes seem remarkably free, and the disease seems to attack 

 only the soft tissues, which have become entirely consumed by the 

 growth of the fungus. 



Dr. Carpenter mentions the fact that it is not at all uncommon in 

 the West Indies to see a species of PoJistes (the representative of 

 the wasp in our own country) flying about with fungoid plants of 

 their own length projecting from some part of their body, their roots 

 having a firm hold of the soft structures within ; and in his work, 

 " The Microscope and its Revelations," he mentions several other 



