282 PEAKLS AND PEARL-CULTURE. 



Sir Everard Home prides himself as the discoverer of 

 the true nature of the pearls. " I shall now explain 

 what a pearl really is ; arid if in the course of my ex- 

 planation I shall prove that this, the richest jewel in a 

 monarch's crown which cannot be imitated by any art 

 of man, either in the beauty of its form or the brilliancy 

 and lustre produced by a central illuminated cell is 

 the abortive egg of an oyster enveloped in its own nacre, 

 of which it annually receives a layer of increase during 

 the life of the animal, who will not be struck with won- 

 der ! In my investigation of the mode of breeding of 

 the oyster and mussel, when the ova were examined in 

 the microscope, we commonly found round hard bodies, 

 too small to be noticed by the naked eye, having 

 exactly the appearance of seed-pearls, as they are called, 

 in the ovarium, or connected with the surface of the 

 shell in contact with the membrane covering it ; which 

 led me to consider this to be the situation in which 

 pearls are originally formed, more especially as here 

 they were not only very small, but uniformly of the 

 same size, and when found more and more distant from 

 this spot they had increased in size. These facts led 

 me to conclude that the ova which prove abortive do 

 not die and drop off at the same time that those which 

 have been impregnated pass into the oviduct, but re- 

 main in their capsules, which, being still supplied with 

 blood-vessels, go on increasing for another year ; their 

 surface then receives a nacral covering with all the 

 other surfaces of the shells, and they lose their attach- 

 ment or become imbedded in the shell ; this is in some 

 measure proved by pearls being met with perfectly 

 spherical others in which the pedicles are included in 

 the nacral coat others, again, more or less buried in 

 the nacral coat of the shell. 



'* As pearls have their origin from so small a nucleus, 

 it is not surprising that there are so few r of a large size, 

 since it is probable that oysters of great size, which 



