THE PRODROMUS 253 



unless another Lucullus should fill his aquaria^ with pearl- 

 bearing mollusks, and either seek in the animals themselves the 

 methods of increasing them, or learn thence the difficulty of 

 imitating the works of Nature. I would not deny that one can 

 P. 57. form, artificially, globular masses consisting of various integu- 

 ments, but to arrange these integuments from a succession of 

 filaments and unite them according to a system, upon which the 

 natural lustre of pearls depends, this I should consider indeed 

 most difficult. 



The shells which lie buried in the earth are reduced to three 

 classes. 



The first class consists of those which are as like the shells 

 just described as an egg is to an egg; since both the shells 

 themselves are resolved into subdivisions, and the subdivisions 

 into filaments ; and there is the same difference and position 

 of filaments. An examination of the shell itself proves that 

 these shells were parts of animals at one time living in a fluid, 

 even if marine testacea had never been seen, as will appear 

 from the example of bivalve mussels. 



At the time when bivalve mussels were formed, the sub- 

 stance contained within the mussel, 



1. Had a smooth surface pierced with countless pores, and 



a twofold variation of pores. 



2. Had a substance pliable and less hard than the shell 



itself. 



3. Was in communication on the one side with the sur- 



rounding matter, on the other had no communication 

 with it. 



4. Gradually withdrew, from the side where communica- 



tion with the outer matter was denied it, toward the 

 side where it had free communication with that same 

 matter. 



' The fish-ponds of LucuUus were famous in antiquity, but our sources do not indicate that 

 he stocked them with pearl-bearing oysters. Nor does Steno imply that he did so. The 

 locus dassicus is Pliny's Natural History, IX, 170 (54): 'Lucullus cut away a mountain 

 near Naples at greater expense than it had cost him to build his villa. He let in the sea- 

 water, and for this reason Pompeius Magnus used to call him the Roman Xerxes. After the 

 death of Lucullus the fish were sold for four thousand sestertia' (more than $150,000). With 

 this may be compared Pliny, N. H., VIII, 211 (52) and Plutarch, Lucullus, 39. 



