48 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



the eggs had not yet broken down. The ovary of the larger lobster was similar to 

 this, but the process of histolysis had not advanced quite so far. 



The eggs are sometimes absorbed under natural conditions, but why this happens 

 is not understood. A very interesting illustration of this fact came to hand on July 

 16, 1894, when, on account of its very dark color, my attention was directed to a 

 hardshell female lobster, about 11 inches long. The membranes of the joints of the 

 limbs and under surface of the body were of a dull-green color, very unlike the 

 appearance which these parts assume in a molting lobster. Examination showed 

 that the ovarian eggs were almost completely absorbed and that the blood of the 

 animal had a very distinct greenish tinge. The ovary was of a bright lemon-yellow 

 tint, the color of the degenerated eggs, flecked lightly with green, where an egg had 

 not lost its normal appearance. The ovarian lobe had shrunken to less than one half 

 its former size. The green pigment which was dissolved in the blood had undoubtedly 

 come from the eggs, and had been taken up into the blood faster than it could be 

 eliminated from it. I was told by Professor Eyder that the ovarian eggs of the 

 sturgeon are sometimes absorbed in a similar way, and the same phenomenon is 

 probably met with throughout the animal series. 



In the lobster there are always a few ripe ovarian eggs which fail of extrusion at 

 the proper time, which are invariably absorbed and give to the mature ovary at the 

 next reproductive period a characteristic appearance. (See p. 69 and plate 38, 

 fig. 136.) 



One of the females which laid eggs had been kept by herself for several weeks. 

 When discovered, on August 21, the ova were in an advanced stage of yolk segmen- 

 tation. They were somewhat undersized and of a peculiar light-grayish color. The 

 eggs were fertile, although the segmentation was generally abnormal. The lobster, 

 which was placed in an aquarium on July 30, was found to have external eggs on the 

 11th of August, in a very early stage of development. They had probably been 

 extruded during the previous night. These eggs were rapidly attacked by fungi and 

 their development was retarded in consequence. Long fungoid filaments grew over 

 the surface of the eggs, and diatoms attached themselves in great numbers to the 

 egg-capsule. The eggs of lobsters taken under natural conditions are always clean 

 and, so far as I have observed, free from vegetable growths of every kind. 



The eggs are fertilized after ejection from the oviducts by the spermatozoa, a 

 supply of which is always stored up in the seminal receptacle of the female. There is no 

 internal copulation, and no possibility of an internal fertilization in either the ovaries 

 or their ducts, as already explained (p. 39). The ova are probably immersed as soon as 

 they are extruded, in a liquid cement substance, which is secreted in special glands 

 situated in the swimmerets of the female. The "tail" is folded so as to form a closed 

 pouch or chamber, as has been observed in the crayfish and other decapods (see 

 note 1, p. 47), and the eggs received within it are mixed with the liquid cement and 

 sea water. Fixation to the hairs of the swimmerets is finally effected by means of the 

 cement, which gradually hardens. How the sperm cells are conveyed from their 

 receptacle to the eggs, whether through the medium of the sea water or the glue, or 

 whether or not by a motion of their own, is not definitely known. (Page 34, note 1.) 



That the cement is incapable of fixing and holding the eggs until after exposure 

 to sea water for some time (perhaps a few hours) was shown in the case of a lobster 





