CIX 



*' tliat each egg wliich floats out into the ocean to shift 

 " for itself will immediately meet with a male cell is very 

 '' slight, and it is essestial that the egg should be fertil- 

 '' ized very quickly, for the unfertilized egg is destroyed 

 " by the sea water in a very short time. The next period 

 " of great danger is the short time during which the 

 " embryos swarm to the surface of the water. They are 

 " so perfectly defenceless, and so crowded together close 

 " to the surface, that a small fish, swimming along with 

 '^ open mouth, might easily swallow in a few mouthfulls 

 *' a number equal to the human population of Baltimore. 

 " They are also exposed to sudden changes of tempera- 

 ' ' ture, and as my experiments have shown that a sudden 

 " fall in temperature is fatal to them at this time, the 

 " number which are destroyed by cold rains and winds 

 " must be very great indeed. 



" As soon as they are safely past this stage, and scatter 

 *' and swim at various depths, their danger from accidents 

 ' ' and enemies is greatly diminished, and their chance of 

 "reaching maturity increases hundreds, and ]3robably 

 " thousands of times. 



" My experiments show that there is no difficulty in 

 '^ developing them up to this point in the house in small 

 ' ' aquaria, and in carrying them safely past the most 

 " precarious part of their lives, and freeing them from 

 " all their greatest dangers." 



The importance of carr^dng the investigations beyond 

 the point reached by Dr. Brooks, induced me to secure 

 the services of Professor J^ohn A. Ryder, of the Phila* 

 delphia Academy of Sciences, and having provided quite 

 an assortment of collectors, I stationed him in the month 

 of July at the mouth of the south fork of St. Jerome's 

 Creek, in St. Mary's County. This creek flows into the 

 Chesapeake a few miles north of Point Lookout. 



Having secured the use of ponds, formed by a prong 

 of this creek, it was my intention to arrange them 

 so as thoroughly to control the ebb and flow of the tide 



