[7] RETARDING DEVELOPMENT OF SHAD EGGS. 793 



reservoir. But this did not seem to stop the death of the eggs, and in 

 order to save the remainder they were transferred at noon of the sixth 

 day to a cone of fresh water at a temperature of about 73°. The stale 

 water had, however, apparently been too injurious to them and they all 

 finally died. It appeared to be pretty evident from this trial that while 

 artificial aeration would increase to a certain extent the time during^ 

 which the water- could sustain the eggs in good condition, yet four and a 

 half or five days were about the utmost limit of time the same water could 

 be used over and over again. When used for this length of time the entire 

 vitality appeared to be taken irom it. This was probably from the using: 

 up of the oxygen contained in it, although the decaying organic mate- 

 rial, sloughs, and dead eggs, of which there are always more or less 

 mixed with good eggs, may have played a very important part in render- 

 ing the water unfit for sustaining life. 



The end of the season was now at hand and good spawn was very 

 difiicult to obtain. We were thus prevented from trying other methods 

 of using the water. The next method would have been to take enough 

 water on board at the beginning of the experiment, in addition to that 

 in the reservoir and cone, to enable us to give the eggs a complete 

 change of water, drawing off the old and putting the other in its place 

 once every three days. 



If unused water — water which contains its normal amount of oxygen 

 and which has not passed over the eggs so as to become tainted with 

 decaying organic material — is all that is required to replace the used or 

 partially exhausted water of the cone, then there would be no difficulty 

 in keeping the eggs in good condition for a voyage of twelve or fifteea 

 days, for it would be an easy matter to carry sufficient water in extra 

 casks to make complete changes every three days for this length of 

 time, or even longer. But as a trip can be made in from eight to nine 

 days, or as that would be the length of time which would elapse before 

 fresh water could be obtained, it would hardly be required to make over 

 two, or perhaps three, changes. From our experience this year it seems 

 highly probable that such an attempt would be entirely successful, and. 

 that a good proportion of eggs thus treated could be hatched out and 

 the young tish distributed wherever it was desired to take them. In 

 such an experiment the larger the amount of water passing over the 

 eggs the longer tbe time required to exhaust it or render it foul. If the 

 experiment should be tried again and for the same purpose, that is^ 

 transportation across the ocean, the apparatus should be just such as- 

 would be em})loyed on ship board, and with the supply-reservoir made 

 as large as could be conveniently carried. Then, by changing the water» 

 aeration, and the use of a filter for the used water before it re-entered 

 the supply-tank, it would seem as if success could be assured. At leasts 

 if this method cannot be made to answer the purpose it is very ques- 

 tionable whether any can. Several cones instead of one could be used, 

 if desired, by simply connecting one cone with the next, each cone tak- 

 ing the outflow from the one preceding. In this case it would be neces- 



