624 OYSTERS, AND ALL ABOUT THEM. 



Independently of verification by means of a microscope, 

 an instrument which few ostriculturists possess, knowledge 

 on this point may be obtained as follows, i . By an exa- 

 mination of the gland. If this gland is transparent at any 

 point, this means that the evacuation of the generative 

 elements has commenced, and, consequently, these ele- 

 ments are mature. (This remark applies to the gland of 

 the male as well as to that of the female). 2. By the 

 separation of the ova from the ovarium. If the ova are 

 easily detached by the simple rubbing of a fine pencil, 

 they may be considered as fit for fertilisation. It may, 

 however, happen that some barren ova may detach them- 

 selves from the gland easily, but this is not the case except 

 when they have received some injury. 



When the seminal liquor mixes easily with the water, 

 it may be assumed that it will act efficaciously.* 



After making these arrangements, and when a recipient 

 has been prepared half or three parts full of sea-water, 

 incisions are made in the ovary gland, and by means of 

 pincers, with fine and flexible points, the ova are detached 

 and placed in the receptacle as fast as they are detached. 

 At this period they must be washed, with the view of facili- 

 tating impregnation. 



* Here the microscope is of the greatest utility, especially if it is 

 desired to ascertain the quality of the fertilising element. In order 

 that this element, which can be examined only with a powerful glass, 

 may fulfil the duty expected from it, it is necessary that the animal- 

 cules which compose it should be distinct, independent, and living. 

 In cold weather they are often observed to be motionless, but this is 

 often when they are merely numbed ; it is enough to expose them to 

 warm air, or to place them in water of 22 or 25 degrees of temperature, 

 in order to awaken vibration and activity. Disintegration is obtained 

 in certain circumstances by the same procedure. Cases of barrenness 

 are generally very rare. 



