THE ABAL0NE8 OF CALIFORNIA 



545 



(«) Black abalone shell with pearl form inserted, (b) Head of shell pearl form 

 on inner side of black abalone shell, (c) culture pearl formed in the green abalone 

 in seven months. 



nacre which we now know serve as minute prisms to split up the white 

 light into the rainbow tints so beautiful when reflected from the surface 

 of the pearl. In the middle of the nineteenth century from an investi- 

 gation of the fresh-water mussels of Turin Lake, Eilippe proved that 

 the stimulus for pearl formation in that species is a trematode worm. 

 Other naturalists, Kiichenmeister, 1856, Mobius, 1857, Kelaart and 

 Humbert, 1859, Garner, 1871, Dubois, 1901, and Giard, 1903, have 

 contributed to our knowledge of the origin of pearls from parasitic 

 nuclei. In 190'?, Jameson traced the life history of a Distomum from 

 its first host, a duck, to a clam as its second host, and he succeeded in 



Interior View of the Red Abalone 

 Shell, showing pearly center within the 

 muscle scar. 



Shell of the Green Abalone. 

 The anterior portion polished. 



