106 OYSTERS, AND ALL ABOUT THEM. 



Upon this point Professor Huxley observes : "It is 

 important to observe, that when oyster fishermen say that 

 there has been no ' fall ' of spat in a given season, all that 

 is really implied is that the young fixed oysters have not 

 made their appearance. The fact of the absence of a ' fall 

 of spat' does not justify the conclusion that the oysters 

 have not bred as usual. It is quite possible that just as 

 many eggs have been deposited in the branchial cavity, 

 and that just as many larvae have been set free as in other 

 years ; but that the larvae have been destroyed by those 

 changes of temperature to which they are so sensitive, or 

 by other causes. But, of course, it is also quite possible 

 that the oysters have been really barren ; or that, although 

 the eggs have reached the mantle cavity, the larvae have 

 not hatched out. Oyster eggs, no less than hens' eggs, 

 may be addled. 



" It is obviously useless to speculate upon the causes of 

 a ' failure of spat,' until, by the examination of samples of 

 oysters from time to time, and by sweeping the superjacent 

 water with a fine towing net, the exact nature of the par- 

 ticular case of failure has been ascertained. There is much 

 reason to believe that the fertility of oysters, preserved in 

 pares, is greatly diminished, although the oysters them- 

 selves may be improved in fatness and quality by the pro- 

 cess, and that this is especially the case when the water in 

 which they are preserved has a low degree of salinity ; and 

 it is very desirable to ascertain the nature of the modifica- 

 tions effected in the structure and functions of the repro- 

 ductive apparatus of the oyster under those circum- 



stances.' 



" I have been lucky enough," continues Frank Buck- 

 land, " to see more than once, in my little oyster observa- 

 tory, the process of ' spatting.' The oyster slowly and 



