Some Habits of the Adults 25 



manipulation which will not destroy it ; and (2) 

 those whose eggs are not thus equipped but which will 

 remain upon the surface of tranquil water by virtue 

 of the air entangled in the reticulated membrane 

 enveloping the individual eggs or which adheres to 

 the spines that in many cases project from it. I 

 think the tension of the surface film, as well as the 

 gelatin between the membrane and the chitin, also 

 helps flotation. The eggs of the first group are de- 

 posited in boat-shaped masses, and Dr. Dupree finds 

 these to be intolerant of any lengthy desiccation, 

 refusing to hatch after seven hours of drying, often 

 after as few as four. He has had the eggs of Anophe- 

 les develop after as many as ten hours out of 

 water, this, however, being exceptional. Ajwpheles 

 eggs often remain for several weeks on the surface 

 without hatching; in one instance they were observed 

 to lie thus dormant for forty-one days. As a rule, 

 however, the floating eggs must soon produce larvae 

 or perish ; hence it was the Doctor's belief that the 

 species possessing such ova must perpetuate them- 

 selves by hibernation as adults, or, in some cases, as 

 larvse. The eggs of group 2 are laid singly, and 

 withstand indefinite drying or submergence. 



He further says it is not true that, as has been 

 asserted, neither the entire egg mass nor a single 

 egg of a broken mass can be sunken, no matter how 

 much they may be shaken about in the water on 

 which they were deposited, for, when separated, a 

 slight agitation causes the individual ova to sink to 

 the bottom, where the wigglers emerge. Why 

 is it that these single eggs of a disintegrated boat 



