148 THE POPULAR SCIENCE MONTHLY. 



resulting young are exposed, unprotected, to all the vicissitudes of 

 climate and to the ravages of all enemies. 



After the formation of the shell, and the development of the loco- 

 motive powers, the young of both varieties begin their search for a 

 permanent resting-place or point of attachment. The swimming period 

 is of short duration, and the powers of locomotion are not very great ; 

 consequently, such points of attachment must soon be obtained, or the 

 young oyster perishes. Any moderately rough, hard substance, pro- 

 vided that the surface is clean, is suitable for attachment, and such 

 objects, when exposed for the purpose of attracting the young brood, 

 are called "cultch." Pieces of wood, boughs of trees, planks, stones, 

 old shells, tiles, and fagots, have all been successfully used. It is only 

 necessary that the surface should be hard and clean, and, if dark- 

 colored, so much the better. Upon finding the " cultch," the " spat " 

 attaches itself firmly, and is thenceforward, so far as its own power is 

 concerned, located for ever ; all future movement and change of posi- 

 tion are due to causes, natural or otherwise, over which it has no 

 control. 



The development now is one of ordinary growth, the animal hav- 

 ing passed through its embryonic life ; its organs are formed and are 

 in active operation ; it is but immature. The increase in size and the 

 development of the different parts, or, in other words, the growth, are 

 much more rapid with the American variety than with the European. 

 Though we have no record extending over any length of time, and 

 none of different localities, yet the observations during the summer of 

 1879 in Chesapeake Bay show that in the first three months of exist- 

 ence the oyster in that locality increases in size from a hardly visible 

 speck to an average length of one and a quarter inch, and a few 

 were over two inches long. The lower and attached side grows the 

 most rapidly, and during this first period the growth is mainly in 

 length ; there is, of course, a development in all directions, but the 

 greatest is toward the lips of the shell. After the first year, the in- 

 crease in size is not so rapid, and oysters of two or three years of age 

 are about two inches broad and three inches long, though those dimen- 

 sions will vary considerably in different localities on account of the 

 different conditions to which the animals are subjected ; in three years 

 at the most the American oyster is considered mature, and will present 

 all the characteristics of those found in the markets. With the P'uro- 

 pean variety the growth is much slower, and at maturity they are very 

 much smaller than the American oyster : but this difference is imma- 

 terial to the question under consideration, and all that is necessary to 

 notice is the consequence of the different methods of propagation. 



With all animals Nature strives to provide against the destruction 

 of the young after birth by insuring a sufficient number to allow for 

 all ravages ; and the greater the dangers to which the immature of any 

 species is exposed, the larger will be the number provided to meet 



