QUAHAUGS FROM NEW BRUNSWICK 77 



SESSIONAL PAPER No. 38a 



due to evaporation of the contained water or that of the organic fluids, for several 

 check experiments demonstrated that the shell remains constant as long as the con- 

 tained moisture lasts. It is reasonable to assume that under such conditions, excre- 

 tion of deleterious gas and secretion of oxygen must decline, and the functional 

 activities of all parts and organs be lowered. The large quahaugs were much less 

 resistant than the small ones, for 90 per cent at least of all dying in the course of 

 the experiments were of that class. 



Just here it may be asked: Does not a considerable percentage of old c^ams 

 normally die every season in consequence of expended energy involved in reproduc- 

 tion, a, number, the greater as the environment becomes the less natural? Very little 

 is known of this and many other phases of its life-history, and until fuller and more 

 definite knowledge is available, economic problems, like that under discussion, cannot 

 be satisfactorily solved. 



When loaded in box-cars, half or more are under a pressure too great to permit 

 the valves to reopen; for, though they are shut and kept closed by contraction of 

 the adductor muscles, they are reopened automatically by the elasticity of a small 

 hinge, too weak, however, to overcome the increased resistance. Hence it was sur- 

 mised that oxygen utilization would be greatly reduced, fatal results foil w, and in 

 the premises the mortality seemed partially accounted for; but in the light of the 

 following experiments it cannot be regarded otherwise than at best a contributory 

 cause, effective only, if at all, in a high temperature and under faulty ventilation. 



August 3, thirteen clams were put under pressure in the laboratory, some in 

 clamps, the rest under heavy weights. At the same time a large one was put into an 

 1800-c.c. jar of sea-water which had been boiled for half an hour to expel the oxygen. 

 The jar was completely filled, so as to exclude all air, and sealed. It was noticed that 

 the siphons were kept protruding as long as it was confined in the jar. The tempera- 

 ture of the room rose above 70° on two occasions, the maximum being 72°, the mini- 

 mum SS'', the mean for the seven days being 62'i°, 61°, 61°, G5|°, (>2°, 66° 66°, or 

 an average mean of 63°. No night temperatures were taken, but they were probably 

 all below 60°. The conditions were certainly very favourable for testing the quahaug's 

 powers of endurance under a fairly uniform temperature, and pointing to a means 

 of minimizing the losses met with in the trade. 



August 10 all were released and placed in trays, where they continued to live 

 until removed at the end of the season. 



The tests exemplify the clam's great resistance to the lack of oxygen. Philip H. 

 Mitchell (vide Bull. U. S. Bureau of Fisheries, vol. xxxii, 1912) demonstrated by 

 carefully performed experiments that forcibly closed quahaugs did not appreciably use 

 any oxygen, but voluntarily closed ones did. His experiments, however, were con- 

 ducted in a water medium, and while the valves may be closely enough set to prevent 

 entrance of that oxygen-bearing element, it may be somewhat different in an air 

 medium. Indeed the ridged character of the margins of the valves would seem to 

 make it probable. One of his most important findings, however, is that oxygen util- 

 ization increases with the temperature, and that the smaller clams show a relatively 

 greater consumption of oxygen than the larger. 



To prove whether ventilation was or was not a valuable factor in provisions for 

 marketing clams, the following experiments were made: — 



(1) A tight box holding thirty-two was closed August 12 and kept in that condi- 

 tion till August 19 under the varying temperature of the room, which ranged between 

 58° and 70°. Before being opened, a thermometer thrust through a hole, just bored 

 for the purpose, registered 2° lower than the room. Three clams were dead and five 

 more died during the next two days in the tray to which they had been transferred, 

 making a total loss of 25 per cent. 



(2) Another lot of eleven was put into a glass jar, the top being covered with 

 perforated cardboard, and the vessel was set in a tray ip 2 inches of water with a jet 



