removed from water could be placed in such surroundings, that after a time on being replaced in water they would hatch out. I found after all my experiments that eggs removed from water for 24 or 36 hours in no case hatched out. This has led me to believe that the different periods are not tided over by eggs. One of my experiments was to place eggs on dry mud taken from a small tank. The mud was put in a small glass vessel, the eggs placed on the mud, and water was then poured into the glass vessel. After two hours I found on looking into the water four or five larvae. Although the eggs did not hatch, this at the time did not strike me as being important, since I thought these larvae seen were in the water which I had taken from a tub in my bathroom.
At the end of April I went home on leave, and so did not carry on any more experiments, although I had satisfied myself that eggs must be put out of court. Oa returning in July this year I made several experiments with larvae, which I need not repeat here as they were failures. On reading through my notes I came across the remark that "there were four or five larvae in glass vessel which contained tank mud on which eggs had been placed." This struck me as being worth while to repeat, but with certain precautions, viz., to use filtered water. In my garden is a small shallow brick tank, the si^e being 2' X 2' x 6'. The tank is in the sun. I examined it and found a certain amount of mud and dead leaves at the bottom. There was about one inch of water, and it swarmed with larvae of culex of various ages, also nymphae and eggs. This was on the 18th of August. On the 2 1st the tank was dry and the mud quite dry. I scraped up the whole of this mud and put it into a box. On the 2l3t I put some of this dry mud into a small glass vase along with filtered water. Two hours after I found two larvae. Some of this mud I put into water every day till September 3rd, when I put it in every other day till the 23rd of September, with the results given in the Table below. On the 28th August, 1st September and 2lst September the results were nil. This may have been due to no larvae being in the mud, or to their having died; anyhow it made no difference, as on subsequent days larvae appeared. A month after, viz., 23rd October, I again put some of the dry mud into water, and found larvae in the water six hours after. The water being much colder in October, hence the delay in the larvae being resuscitated. The last of this mud I placed in water on November 16th, and found two larvae after seven hours. I have some other mud which has now been two months perfectly dry, and which gives me good results on being placed in water. From this mud I shall continue the experiment. I am certain that if, after complete desiccation, larvae can be resuscitated after nearly three months, then they will come to life after a much longer period. On referring to the Table, it will be seen that only those larvae of about two to three days old survive. I have never found any older or any nymphae, although the water contained larvae of all ages, also nymphae and eggs.
In these experiments, it may be said, that the eggs, which were also present, hatched out.
I do not think so for the following reasons:—
1st — Experiments carried out in April 1901 on eggs gave no results.
2nd — I could find no eggs in the mud after being placed in water.
3rd — The size of larvae were much too large for newly hatched larvae.
4th - The short time in which larvae appeared in the water.
Everything points to the fact that the larvae present were not recently hatched. All larvae ran their usual course and became mosquitoes, as will be seen on referring to Table. On referring to Giles' excellent book on Gnats and Mosquitoes, second edition, page 123, the following will be found:—"Desiccation, on the other hand, was better borne by the nymphae, which in a few days were transformed into very active mosquitoes, in spite of being placed in dry river sands, so that a drying up of a pool does not stop the development of such insects as have reached this stage, while the larvae were all dead in two days if dried at 200., and both stages were killed by two minutes' exposure to a temperature of 400. Experimenting in India I found that larvae were usually dead and decomposed before the mud of the pool in which they had lived had dried up by ordinary evaporation."
In my experiments I found that all larvae over three days old or thereabouts did not revive—in fact all my first experiments ended in failure, as I had experimented on larvae of six, seven or eight days old. I also find that they do not survive in mud taken from every tank. I am now experimenting as to the conditions, i.e., to ascertain if the water has to be rapidly evaporated in the sun, or out of the sun. Time of year:— The experiment in 1901 was in April before the rains, and the one in August after the rains. Season may have something to do with it. No nymphae have ever survived in my experiments; but in future experiments they may prove to do so. The facts which I have up to date verified are:— That Culex larvae of a certain age can survive after nearly three months' complete desiccation. No nymphae or eggs have survived after desiccation. The larvae that have been resuscitated run the usual course and become mosquitoes. If this is true for culex, I am almost sure that the same will hold good for anopheles, in fact, in one of my experiments on anopheles larvae I believe that they did survive. The experiment was not completed, as an accident happened to the glass vessel, a rat having knocked it over.
I have not been able to carry out any more experiments with anopheles because with, the
