64 CONFERENCE OF GOVERNORS. 



vidual responsibility, and guaranteeing property rights to the 

 product of his labors. The fisherman should, by definite laws, have 

 the right to increase by his own efforts, through cultivation, the 

 yield per acre of the tidal flats, and should be encouraged to de- 

 stroy such animals as act as checks upon economic production. 



Life History. 



In order that the conditions may be understood and the possible 

 developments be properly judged, it is necessary to giv§ a brief 

 outline of the life histories of the mollusk group, and then to indi- 

 cate how certain facts in the life histories of each species make 

 possible a vastly increased production of the edible moUusks. 



Fortunately for our present purposes, the general and important 

 features ia the early life histories of the clam, quahaug, scallop 

 and oyster are so similar that a general description applies to all. 

 Between the first of June and the first of September the eggs and 

 sperm of all these species become mature, are discharged into the 

 water, and are borne about to a considerable extent by the cur- 

 rents. One large mollusk may produce many millions of eggs or 

 sperm, but only a very few survive. An egg soon after beiag laid 

 may chance to be fertilized by a sperm, which, swimming about in 

 the water, meets and bores actively into the egg substance until 

 the sperm nucleus fuses with the nucleus of the egg, after a series 

 of extremely complicated but rather definitely known changes. 

 Within a few minutes after fertilization the cell material begins 

 to be divided into a number of similar but progressively smaller 

 portions or cells. Soon these cells, at first similar, assume different 

 and specific characteristics, ultimately becoming special portions 

 or organs in the animal, e.g., stomach, intestine, skin, mantle, 

 heart, gills, nerves, blood vessels, foot, reproductive glands, etc. 

 About eight to twelve hours after fertilization the egg hatches. 

 The larva bursts the egg shell, and, by means of actively moving 

 hair-like projections of its superficial cells, swims to the surface 

 of the sea. A primitive stomach is soon formed, and the free- 

 swimming " gastrula " begins to feed upon such microscopic plants 

 as bacteria, small diatoms, etc. Within perhaps twenty-four hours 

 the shell begins to form. It gradually increases in size, spreading 

 over two sides of the body, which slowly flattens. Within the part 

 covered by the shell, characteristic folds appear which ultimately 

 form the gills. The part outside the shell retains its cilia (the 

 vibratile hair-like projections) upon the surface ceUs, and becomes 

 an organ of locomotion, the velum. Soon by the side of the velum 



