MOSQUITOES. 89 



cutting the skin. All but the sheath enter two-thirds their full length before 

 they begin drawing the blood, the sheath doubling up under the body of the 

 insect. 



The manner in which the mosquito draws up the blood to satisfy its crav- 

 ings is probably similar to that by which a butterfly secures the nectar from 

 the flowers. Let us consider the long proboscis as lips, the mouth proper 

 being situated in the head at their base ; when the lips have entered the fluid 

 the muscles around the mouth are contracted ; that produces a cavity which 

 is necessarily a vacuum, and the fluid naturally rushes in to fill it. When it is 

 filled the muscles around the mouth relax, a valve at the base of the lips 

 closes and prevents its return, and the fluid is forced down the gullet. 



The rapidity with which the mosquito thus pumps up the blood, and the 

 quantity it secures in a given time, may easily be observed by any one curious 

 to know by allowing one of them to operate on the back of the hand and 

 watching the filling up of the abdomen. I once clipped the end off the 

 abdomen of one thus situated without disturbing its operation, and it pumped 

 away until a pool of blood that had run through it formed on the back of my 

 hand and began to run off, when I stopped the performance. I had been 

 informed that this could be done before I succeeded in doing it. 



No poison gland has yet been found in the mosquito, but the irritation 

 resulting, and often continuing long after the bite is given, has led to the 

 general conviction that poison must be conveyed with it. One writer relates 

 that a drop of clear fluid has been observed at the end of the trunk, whilst 

 Reamur says he saw fluid in the trunk itself. Some contend that this fluid 

 is used for diluting the blood so as to enable it to pass through the extremely 

 fine tube, but the quantity that they produce is so small, as compared with the 

 amount of blood they take, that it could have but little effect in that way, 

 unless it was endowed with some powerful chemical property. Some have 

 stated that if they are allowed to take all they want, there will be no after 

 irritation, the poison being all removed with the blood taken. But personal 

 experiments in this direction do not confirm the statement. 



There is a great diversity in the effect of the mosquito bite on different per- 

 sons, just as there is in the sting of a bee, not from any difference in the 

 sting and bite, but from something in the constitution of the individual. The 

 Rev. J. G. "Wood tells us of the effect of a single gnat-bite on himself, given 

 at the junction of the thumb with the wrist. (It is culex pipiens he is speaking 

 of.) He says : " The hand swelled up until it looked like a boxing glove, was 

 purple in colour where it was not crimson, and it was more than three weeks 

 after the bite was inflicted before I fully recovered the use of my hand." 

 This may be considered a serious case, and if he had received several bites at 

 the same time, some of them about the face we shall say, there is no saying 

 how much more serious it might have been. I copy the following from a 

 1? 



