ATKINS THE SALMON AND ITS ARTIFICIAL CULTURE. 261 



development is the additional expense attending it, and I tliink this is 

 fairly counterbalanced by the longer time afforded for packing up and 

 distributing the eggs, and by having the hatching delayed until the 

 natural period, when all the conditions existing in the water may be 

 supposed to be best adapted to the healthy growth of the young fish. 

 The water in the streams where salmon naturally spawn is quite as 

 cold as that used in this hatching-house, and the incubation of eggs 

 there goes on quite as slowly. During incubation one man can, under 

 ordinary circumstances, take care of several millions of eggs. There 

 is little to be done except to pick out those that die and turn white, 

 before they decay and contaminate the water. In water of 34° F. decay 

 begins so tardily that once a week is often enough to take out the dead 

 eggs. This was done in the present case with wire-pointed wooden 

 pliers, without removing the trays from the trough. Some fish culturists 

 remove the trays to a table, where the work can be done easier, but my 

 own experience leads me to believe that at certain stages of develop- 

 ment tlie eggs will not endure the disturbance involved without injury. 

 The number of dead eggs taken from the troughs was not larger than 

 ordinary until about the 1st of January. At that time tiie number dying 

 from day to day suddenly increased, and was very large during the 

 rest of the season. The percentage lost in this way at Orland the 

 previous season was but a little over 2 per cent, of the number of eggs 

 taken. At the same rate the number this year should have been only 

 about 32,000. Actually it reached the large total of about 318,000 or 20 

 per cent, of the whole. This extraordinary mortality requires explana- 

 tion. It was due to a variety of causes. First, the windows had been 

 curtained only with cotton cloth, and this admitted an amount of light 

 that encouraged the rank growth of a species of coufervoid vegetation 

 which spread over the eggs like a blanket, shutting them out from a 

 due supply of water from the current flowing above them, and exposing 

 them to the influence of the water beneath the trays. Second, the space 

 underneath the trays was too narrow for so long troughs as 60 feet; 

 there was little or no current through it, and the conferva prevented a cir. 

 cuhitiou through the trays. Thus this space was occupied by stagnant 

 water, which soon became surcharged with noxious substances, tbe exu- 

 dations from the wooden troughs and the decay of eggs that accident- 

 ally slipped down beneath the trays, playing an important part. With 

 a suitable current of water all these injurious substances would have 

 passed off before they had accumulated sulficiently to do harm. But 

 in the stagnant water they rapidly accumulated, and, coming in contact 

 with the eggs above them, destroyed them by thousands. Third, a long 

 stove-pipe ran above one of the troughs; tiie liquid condensed within 

 it in cold weather was carried away in a gutter, but on several occa- 

 sions considerable quantities of this poisonous liquid found its way into 

 the troughs.* 



* The causes second and third might have been avoided by the use of covers to the 

 troughs, and these have since been made. 



