BULLETIN OF THE UNITED STATES FISH COMMISSION. 327 



with them. The fecundation is effectual, cleavage sometimes proceeds 

 to an advanced stage, bat all at once the development is arrested, the 

 eggs undergo alterations, and their membrane ruptures. 



To avoid all inconveniences of this kind it is best to usespawners taken 

 from active and deep waters. It is also important to assure one's self 

 that the sexual products used are quite mature.. In the absence of any 

 means of verification by means of the microscope, an instrument pos- 

 sessed by lew ostraeulturists, the following methods are to be resorted 

 to: First, by an inspection of the genital gland. If it is transparent 

 at one point, it shows that the evacuation of the generative products 

 has commenced, and that consequently those elements are mature. (This 

 remark applies to the gland of the male as well as to that of the female.) 

 Secondly, by freeing the eggs from the ovary. If the eggs are easily 

 detached, by simply stroking with a fine camel's-hair pencil, we may 

 consider them fitted for fertilization. It seems, however, that infertile 

 ovules detach themselves easily from the gland, but that this does not 

 take place unless the spawning oysters have been injured. 



Finally we find that the seminal liquor seems to act most efficiently 

 when it mixes readily with the water,* This disposition noted, and 

 after having prepared a vessel one-half or one third full of sea-water, 

 au incision is made in the ovarian gland, and we detach the eggs by 

 means of a soft, flexible brush or pencil, from which they are deposited 

 in the vessel as fast as they are removed. We find that their impreg. 

 nation is facilitated if they are subjected to a washing at this time. 



This operation purges theai of impurities which are still adherent, 

 .and brings about the dissociation of those which still stick together. 

 With this object we shake the contents of the vessel with the hand or 

 stir them with the pencil, when the liquid is allowed to settle. In one- 

 half to one hour afterwards the uninjured ova have settled at the bot- 

 tom of the vessel ; that which remains in suspension in the water; vitel- 

 line matters, ruptured membranes, injured eggs, &c, is to be poured 

 off. It is of advantage to repeat this process of decantation. 



The seminal liquor [milt] is obtained by the same means as the eggs, 

 but there is no necessity for any preliminary preparation. It is simply 



"The microscope is now of the greatest utility, if we wish to assure ourselves of 

 the quality of the fertilizing element. This element, in order that it may serve its 

 purpose satisfactorily, when examined with a sufficiently strong magnifying power, 

 it is necessary that the animalcules of which it consists should appear segregated, 

 independent, and active. During cold weather they are often immobile, hut they are 

 often only benumbed ; it is then only necessary to expose them to warm air or place 

 them in water at a temperature of 22° C. to 25° C. (71° F. to 77°F.), in order to cause 

 them to vibrate and display activity. Segregation of the spermatic particles may be 

 produced under certain circumstances by the same process. Cases of infertility of 

 the milt are generally very rare. [The segregation or dissociation of the seminal par- 

 ticles or spermatozoa by diluting the sperm with water is an important fact, and one 

 that has thrust itself upon the notice of the translator in observing the fresh milt of 

 both oysters and fishes. It seems quite inactive in some cases before dilution; its 

 activity is then at once provoked by the addition of water. — Ti:. ] 



