XXVII -EXPERIMENTAL INVESTIGATIONS UPON COD HATCHING 

 AT WOOD'S HOLL, MASS., DURING THE WINTER OF 1880-'«1. 



By Marshall McDonald. 



In November, 1880, a station was established at "Wood's Holl, Mass., 

 with a view of continuing the experiments in cod-hatching which had 

 been conducted at Provincetown the previous winter. Capt. H. C. 

 Chester was in charge of station, which was equipped with engine, 

 pumps, and reservoir for the purpose of securing constant circulation of 

 salt water through hatching apparatus. Having submitted to the Com- 

 missioner plans of an apparatus which it was thought would be adapted 

 for the hatching of floating eggs, I was directed by him to i)roceed to 

 Wood's Holl and conduct the experimental investigations there. 



The form of apparatus first proposed was an inverted funnel, the 

 lower end of which dipped below the surface of water contained in the 

 trough, upon which it rested, the supply of water being brought in by 

 a tube at the upper or smaller end of the funnel, so that when once 

 filled with water the column was maintained by the pressure of the air. 

 In this way the movement of the water through the cone, or funnel, was 

 similar to that in the ordinary upright cone used for hatching heavy 

 eggs, except that the current was from above down instead of from be- 

 low up. It was supposed that the buoyancy of the eggs would counter- 

 balance the downward movement of the current of water, so that the 

 eggs would be kept in suspension in the funnel. This apparatus an- 

 swered very well for a few days after impregnation of the eggs, when 

 they were much more buoyant than at a subsequent stage. In a short 

 time, however, either by becoming loaded with sediment, or by actual 

 increase of specific gravity, the buoyancy' became less and less, and the 

 eggs were carried out and lost. This apparatus, though promising in 

 results on first appearance, ])roved in practice to be a failure, no eggs 

 whatever having been hatched in it, the several lot^ used being entirely 

 lost. 



As all eggs require constant accessions of fresh water in order to 

 secure develoi)meut, it was evident that some form of a])paratus must 

 be had recourse to in which tlie water could be continually renewed 

 without carrying off the eggs in its efflux. These eggs being buoyant 

 and occui)yiug a layer at the surface of the water, it was tliought that 

 by introducing the water into the lower part of the vessel containing 

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