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the C. pipiens females always without blood in the intestine; a few days after I 

 found the females in the hibernating places, also here without blood in the intes- 

 tine. I cannot see how we can combine these observations with the supposition 

 that the fat body derives from blood nourishment. We further know that the blood 

 nourishment of 0. lutescens is converted into eggs in the course of about eight days in 

 summer, and we shall see that this is also the case with the blood nourishment 

 in May in the case of C. pipiens. It is therefore in my opinion rather hazardous to 

 suppose that in the course of a few days the blood nourishment in September will be 

 transformed into diffuse fat-masses in the body cavity, and in May into egg-masses. 



For my own part I am inclined to suppose that the fat-body of the hibernat- 

 ing C. pipiens females derive from those fat-masses, which the animal has accumu- 

 lated during the larva stage in freshwater, and which it, passing the pupa stage, 

 has taken over into the imago stage. I know very well that this supposition meets 

 with great physiological difficulties. The question is, whether fat in some more 

 condensed form, taken over from the larva stage into the imago stage, may be 

 further utilized in this stage in any way. 



Even if the physiologists say that this is an impossibility, I should like a 

 'thorough physiological investigation upon this point. It must be remembered that 

 the females of C. pipiens, which we catch in summer, are all relatively meagre, 

 differing much from those in the hibernating quarters; as the C. pipiens were hatch- 

 ed in the middle of September in the water barrels in my garden and immediate- 

 ly began the mating dances only a few meters from the water barrels, and as 

 only a few days later, after a rainy period, I found the females fat and with empty 

 intestine in the hibernating place in my cellar, I suppose that we here have to do 

 with a fact which strongly calls for a more thorough physiological investigation. 



In the course of the winter the mosquitoes become more and more meagre 

 a transverse section (Fig. 18b) gives quite another picture; the form of the body 

 is another and the fat body strongly reduced. One day in April — May they leave 

 the wintering localities like a cloud. Never being bitten by C. pipiens in late spring 

 and summer I have only found the females gorged with blood on the walls of 

 cowstables and hen-houses; cross-sections (Fig. 18c) of the abdomen from blood- 

 filled C. pipiens and from those about eight to fourteen days later, show quite the 

 same picture as we saw in the case of O. lutescens; an enormous gorged inestine 

 filled with blood coagula and eight days later an empty intestine and the body 

 cavity filled with eggs (Fig. 18 d). The above-named cross-sections of the ab- 

 domen of the female mosquito at different times of the year are of particular inter- 

 est with regard to the knowledge of the great phases in the life of the mosqui- 

 toes. In some ways they are even more than that. They represent cross-sections 

 through the life history of the mosquitoes; especially those of the blood-tilled inte- 

 stine and of the abdomen, distended by eggs, represent pictures of the results of 

 the two great life preserving agencies: "Hunger und Liebe" the first acting as life 

 preserving factor for the individual itself, the last for the species; when both have 



