SETTLEMENT OF THE EMBRYO. 



115 



FIRST APPEARANCE OP 

 THE EMBRYO. 



if only one in a million lives through, it will be enough to preserve its 

 race from extinction. Thus, as it were, young oysters uncountable are 

 cast into the ocean to be scrambled for by a host of fishes and small fry. 



But when the minority that have escaped destruction, between the 

 Scylla of ill-tempered water and the Charybdis of hungry mouths, are 

 ready to affix themselves to some solid basis, where 

 they may remain stationary through life, then Nature 

 begins to help them. Heretofore she has trusted in 

 luck and the power of numbers. Now that the ranks 

 are perilously thinned, she gives the remnant of oys- 

 % ~ ' "^^ ter-waifs that persists the rudiments of what will be- 



" l come an armor for their protection, perceivable as yet 



only by the trained eye of the inicroscopist, for a hun- 

 dred of these embryos, side by side, would measure no 

 more than an inch. 



The hours of the infant oyster's swimming are 

 now over. The embryo sinks slowly to the bottom. If it alights upon 

 ooze or a slimy surface it smothers, or dies in the vain attempt to get 

 foothold. If, luckily, it strikes the cleaner surface of an old reef of dead 

 shells, a rock, a pebble, or lately submerged 

 stick, then the pin-head of jelly attaches it- 

 self to a spot whence it will rove no more. 



Even before this time of becoming sta- 

 tionary, microscopists can detect in the sim- 

 ple organization of the little creature the 

 rudiments of the armor of defence. These 

 consist of a crust of two pieces lying on each 

 side of the body, and joined over the vitals 

 by a hinge which permits a slight movement; 

 from them will develop the future " shells." 

 Small as it is, now that it has fixed itself 

 for all time, the little oyster must begin to 

 breathe, as its parents did before it. " Like 

 them its gills soon grow as little filaments covered with cilia, which cause 

 a tiny current of water to pass in and out of the shell. The reader's 

 imagination may be here allowed to estimate the feeble strength of that 

 little current which is of such vital importance to the tiny oyster, and the 

 ease with which it may be stopped by a very slight accumulation of dirt." 

 This liability to smothering is the first of his obstacles. Escaping it 

 he increases in size rapidly, but his ranks are thinned by crabs and vari- 



AN OYSTER ONE YEAS OLD, SHOW- 

 ING EMBRYONIC SHELL AT THE 

 APEX, AND LINES OP SUBSE- 

 QUENT ADDITIONS. 



