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THE AMERICAN NATURALIST [Vol. XL 



for attachment of eggs, and this is more readily reconcilable with 

 the idea that a secretion flows out over the cleansed surface to 

 fasten the eggs than with the idea that the hairs puncture the egg- 

 case and so liberate the material for fixation. 



The " perivitelline space" which is held by Williamson to con- 

 tain the adhesive material in crab's eggs seems to exist in Cambarus 

 as the result of strong, abnormal osmotic changes only, which 

 may accumulate liquid between the inner and the outer parts 

 of the egg-case, when for instance an egg is plunged into strong 

 Flemming's liquid this may accumulate in local blisters of the 

 outer membrane. 



Ovarian eggs were not sticky unless allowed to dry upon the 

 surface when they, either ivith or ivithout the enclosing cellular 

 follicle, stuck to a needle and might be pulled up into club-shaped 

 drops that then sprung up to hang as bulbs connected to the needle 

 by a minute stalk. 



The glaire, however, sticks slightly to dishes and to a knife 

 and when eggs were taken out of the glaire from the front part 

 of the abdominal chamber where they had not yet made stalks 

 (though others in the back part had done so) and put into a watch 

 glass of glaire, they stuck together more firmly than when left 

 in water. The connection of these eggs with one another after 

 48 hours was by delicate fibers something like early stages of egg 

 stalks and such eggs after fifty-eight hours were elastic so that 

 they rebounded five or six inches when dropped nine. Thus in 

 glaire the elastic case and something like a stalk were made when 

 isolated from pleopods and hairs. Again, eggs broken off from 

 very young stalks and left in moist air adhered together very firmly 

 and also to a dead pleopod. These facts seem more readily ex- 

 plained by the action of the glaire than by an assumed early 

 pricking of the hairs. 



A microscopic examination of the material that binds the plu- 

 mose hairs together, made some hours after the eggs were laid, 

 showed that in some places this mass was a dense, clear, highly 

 refracting sheet, moving and breaking under pressure like a stiff 

 jelly, and identical with tlie stalks of eggs, while in other places 

 the material on the hairs was a milky gra\- matrix that rounded 

 itself off like a viscid fluid when broken and was full of droplets 



