722 NATURAL HISTORY OF AQUATIC ANIMALS. 



more or less parallel disposition of the seminal tubules of the testicles or milt of fishes and higher 

 animals. 



In microscopical cross-sections of the adult Oyster, whether it be male or female, the repro- 

 ductive glands are found to be composed of a great number of minute pouches or follicles. In the 

 gross arrangement of the follicles no difference between the sexes is discernible when thin sections 

 are scrutinized with the microscope. Upon making an examination of the contents of the follicles 

 with the microscope a great difference at once becomes manifest; in the male the spermatic 

 particles in the follicles appear very finely granular, and if mature the tails or flagella of the 

 spermatic particles tend to be directed toward the outlet of the follicle; in the female, sections of 

 the follicles show the eggs in various stages of development attached by their narrow extremity 

 to the walls of the reproductive saccules. The egg is pyriform in shape while still in the ovary, 

 but the stalk is not as long as in the eggs of Scrobicularia, as described by von Jhering. As 

 elsewhere stated, the oyster-egg is not globular when first extruded. It will be readily understood 

 that the sexes may be very readily distinguished by these and other marks observed in sections. 

 The immature ova are vastly larger than the spermatozoa, which measure under the ten-thousandth 

 of an inch at their largest end. The head of the spermatozoon of both the American and European 

 Oyster is globular; that of the spermatozoon of the Soft Clam (Mya) is ovoidal in form. The tail 

 or nagellum of the spermatic particle is the locomotive organ which lashes back and forth very 

 rapidly and propels it through the water and finally brings it into contact with the egg. 



213. NEW METHODS OF DISTINGUISHING THE SEXES AND OF TAKING THE EGGS OF 



THE OYSTER. 1 



DISCRIMINATION OF THE SEXES. One of the first requisites of a practical system of arti- 

 ficial fertilization of the eggs of the Oyster is a means which, in the hands of unskilled persons, 

 will enable them, without the aid of a microscope, to infallibly distinguish the sexes apart. Such 

 a means we now propose to describe. Having tested it practically, and found it possible to 

 instruct persons of ordinary intelligence in a few minutes, we have no hesitation in offering an 

 account of the method so as to make it more generally available in the hands of those who may 

 be interested in this subject. 



It is premised that the spawn is squeezed from the reproductive glands by the method to be 

 described further on. As soon as the spawn is emitted from the generative opening in consequence 

 of the pressure exerted upon the gland and the ramifications of its ducts, it is drawn up by means 

 of a small pipette or medicine dropper, provided with a small collapsible bulb at the upper end 

 which is held between the thumb and forefinger. Pressing the bulb between the fingers, then 

 immersing the open end of the pipette into the extruded spawn, and then allowing the bulb to 

 expand by its own elasticity, it will draw or suck up the spawn which has been pressed out very 

 neatly; and if one is careful, absolutely nothing but the spawn is picked up. One soon becomes 

 very expert in the use of the pipette. 



The next requisite is a shallow glass dish, or even a plain tumbler will answer, into which 

 say a half gill of clean sea-water has been poured. Taking up the extruded spawn from the 

 oiening of the duct it is dropped from the pipette into the clear water. This last simple operation 

 enables us to tell without fail to which sex the products belong. If the creamy white mass consists 

 of eggs which have been pressed from the generative openings and is dropped into the water, it will 

 at once break up into a granular cloud as the spawn strikes the latter, the granules themselves 



'The observations and experiments discussed in this article were conducted at Saint Jerome's Creek during the 

 months of July and August, 1882. 



