CONSERVATION AND INCREASE OF PRODUCTION 115 



"Rearing oysters from artificially fertilized eggs," "The oyster problem 

 solved," "The oyster problem actually solved," "A new system of oyster 

 culture," "An exposition of the principles of a rational system of oyster 

 culture, together with an account of a new and practical method of obtain- 

 ing oyster spat on a scale of commercial importance." Ryder's methods 

 were to raise young larvae by artificial fertilization and to turn them out, 

 either at high tide, or through a canal, which might be either open or 

 provided with a filter, into natural or artificial ponds connected with the sea. 

 He believed that since oyster larvae diffuse themselves throughout the three 

 dimensions of a body of water, to obtain good catches of spat it would 

 be only necessary to put in their way immense surfaces of cultch. His 

 plan was to insert numerous perforated trays bearing shells, or vertical 

 strainers filled w'th shells, in the canal leading to the pond, so that the 

 water carrying oyster larvae would pass among them with the rise and 

 fall of the tides. 



Nelson has been at work in New Jersey since 1888 and has made 

 numbers of valuable experiments and observations. To use his own 

 words (1904, p. 420): 



"Our ultimate aim is to establish a system of oyster culture that shall be as 

 much under control as is fish culture." 



He raised larvae from artificially fertilized eggs and tried to keep 

 them in tumblers, tanks, boats, claires, pockets of different kinds of cloth, 

 dialyzers of paper, etc., until they would set as spat. The first part of 

 the process— the raising of larvae to young shelled stages — has been very 

 encouraging, but the last part — the obtaining of spat — has met with 

 little or no success. 



It might be going too far to say that failure was always due to the 

 same cause, but there was a cause common to all these cases sufficient to 

 account for the failure. Rice, Winslow, Ryder and Nelson, all worked 

 under the mistaken belief that the larvae, when still in the straight-hinge 

 stage and about two to five days old, settle down and aflftx themselves 

 to become spat. This mistake arose from chance observations of young 

 artificially-reared larvae temporarily or abnormally clinging by velum 

 or mantle. 



In 1901, Nelson wrote: 



"The fry, after about five days, develop a two-valved shell and then the}' seek a 

 place to settle down on." 



He did not free himself from this view until 1907: 



"It is usually stated that the developing oyster swims around in the water about 

 a week, or less, before it sets on cultch. Last year we were inclined to believe that the 

 interval of free life was less than two days and we felt that this view was not only corrobor- 

 ated by our own observations, but also by those of Colonel Macdonald, the lamented 

 brilliant chief of the United States Fish Commission. Our studies this year seem to 



emphatically negative such views In this stage, called the protoconch stage, 



there is steady growth for at least a week, and possibly three weeks The 



actual size of the larval shell at times of setting is one-fiftieth of an inch in length." 



