3IO BULLETIN OF THE BUREAU OF FISHERIES. 



eggs are attached exclusively to the long silken tufted hairs of the inner branches of 

 the second, third, fourth, and fifth pleopods. They are distributed, therefore, in 8 

 bunches, with over half a million eggs to a bunch. The appendages are flattened, and 

 excepting the anterior face near the tip and a portion of the posterior face near its base, 

 the endopodite is studded with remarkably long silken setae. Each hair carries from 

 150 to 200 eggs, and each egg is glued by an independent stalk to the hair. Each egg 

 is, moreover, extremely minute, measuring about j^-g of an inch (//j- mm.) in diam- 

 eter, or smaller than the dot of the letter i of this type. The hairs are extremely 

 slender, varying in diameter from -^-^ of an inch at base to j^-^ of an inch at middle, 

 beside which a human hair is very coarse and a silken thread a veritable cable. These 

 attenuated hairs taper gradually to a sharp point. 



The exopodite of the swimmeret is fringed with a dense row of plumose setae, which 

 are not more than one-fifth as long as the egg-bearing hairs of the inner branch and 

 which, according to Williamson, serve in Cancer as a barrier to prevent the escape of 

 the ova from the brood-chamber before they become attached. Strange to say, they 

 do not catch a single egg. 



Upon the theory of Williamson, and the assumption of an average cargo of 

 4,500,000 eggs, we can appreciate the nice work in fencing which would have to be per- 

 formed by the silken hairs of Callinectes and indirectly by the appendages of the crab. 

 Some 22,496 hairs would be required to spear and string 200 eggs each, and the feat 

 would have to be done in the dark, as it were, and upon an egg so small as to be hardl/ 

 visible upon the point of a fine cambric needle. But this is not all; the thrusts of the 

 hairs must pierce a periviteUine space, that is, penetrate a tough chitinous membrane 

 and be deflected from a senuliquid envelope. If this really happens, it is certainly a 

 most wonderful performance. 



Our objection to such a theory of attachment is based upon general principles, 

 and before accepting it we should wish to have answers to the following questions. 

 How is it possible for these deUcate hairs to spear anything, and least of all soUd spheres 

 like an egg, suspended in water, and therefore in unstable equiUbrium? The hairs 

 have no more rigidity than a silken thread; they can hardly stand alone; and when 

 loaded with eggs at their tips the spearing of additional eggs would seem to be impos- 

 sible. (2) How is it possible for a spear or needle to penetrate the tough outer coat and 

 avoid piercing the egg, for the suppositional inner membrane really does not exist at 

 the time the egg is laid ? (3) Are the almost microscopic eggs pushed along like beads 

 on a string or birds on a spit, 200 or more crowded in line, and each leaving a viscous 

 trail, without clogging the line, sticking together, or crowding one another off ? (4) How 

 is it possible for drops of an albuminous liquid to ooze from a hole in an egg without 

 spreading over that egg, for a hair in contact with the egg would certainly not conduct 

 this liquid against the force of gravity, and myriads of eggs must occupy every position 

 with respect to the hair? Perhaps we can get a better idea of the physical difficulties 

 involved by imagining a fly-fishing rod reduced to great tenuity and used as a spear 

 for apples. How many apples of whatever size could its tip hold? 



