442 



Bulletin American Museum of Natural History. [Vol. XXXV, 



Mr. Vives obtained his concession from the Mexican government in 

 1903. His brief report 1 relates to the years 1906-07. Considerable time 

 must have been spent in preparation and experimentation. 



From what is known of the pearl oyster in other regions, the shells grow 

 large enough for industrial uses in about four years. They continue to 

 grow after that period of course, but suffer deterioration from worms and 

 boring sponges. What Mr. Vives had to say concerning the formation and 

 growth of free pearls is interesting, and is presented here without comment 

 as this has been a subject of much scientific and unscientific discussion. 



Fig. 37. Forms of wire apparatus for the protection and handling of pearl oysters laid out for 

 growth. 



New pearls are secreted by pearl oysters of all ages, but chiefly by the 

 younger oysters. After the pearl oyster is three years old fewer pearls are 

 formed. 



Pearls ai'e seldom found except during the period from August to Decem- 

 ber and rarely as late as December. Mr. Vives exhibited a small but 

 perfect pearl in the flesh of an oyster of artificial growth known to be only 

 three months old. 



He finds the pearl to be formed within a watery blister (epithelial sac) 



1 Compafiia Criadora de Concha y Perla de la Baja California, By Gaston J. Vives. Informe 

 rendido por la Direction General a la Secretaria de Estado y del Despacho de Fomento, Colonization 

 e Industrie, sobre los trahajos emprendidos durante los anGs de 19(K> y 1907. 



