126 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



If the egg be examined 6 or 8 hours after it is fertilized, the germinal 

 disk will be found to have contracted to a saucer-sliaped cap extending 

 over about a fifth of the surface of the yolk. It is smooth and even, 

 gradually thinning to a sharp outer rim, with a thickness in the center 

 of the cap of about a fifth of its diameter. At this stage — segmentation 

 not having commenced — the impregnated eggs can not be told from the 

 unimpregnated ones. At 18 hours segnienta.tion will be well advanced 

 and the disk will have contracted into six or eight rounded nodules of 

 uneven size, with well-defined valleys between, there being no longer 

 a shari) rim to the disk. At 24 hours — the best time to determine 

 the percentage of live eggs — the disk presents a somewhat similar 

 appearance, except that it will be divided into 25 or more segments, 

 easily seen under the glass; the disk of the unimpregnated egg of 

 the same age forms an almost exact hemisphere, is perfectly smooth 

 in appearance, and is therefore easily distinguished from the live egg. 

 Segmentation now goes on rapidly, and at 72 honrs the cells look under 

 a 1-inch objective — a suitable power to use in this work — about the 

 size ot a mustard seed, the disk having in the meantime assumed an 

 heniisi)herical shape. 



During the entire period of incubation, but more especially during 

 the early stages of growth, the eggs should be worked as gently as 

 possible; that is, only sufticient water should be used to keep them in 

 slow motion and to prevent "banking." At the commencement they 

 require about quarts of water per minute to the jar, but later they will 

 run with a quart less per minute. The eggs require constant watching 

 for the first week or more, and although not considered an adhesive egg, 

 agglutination takes place occasionally when the water becomes roily. 

 Unless the "banks" so formed are separated by gently stirring them 

 with a long feather (the long wing feathers of a turkey are suitable), 

 the eggs forming the pack soon die and form a mass in the jar. 



In a few days, varying with the temperature of the water, the unim- 

 l^regnated and other dead eggs begin to "fungus" — that is, a growth 

 makes its appearance on them and they rise to the toj) of the egg mass — 

 when they must be removed by the use of a siphon, and if live eggs are 

 among those drawn off, they must be set up in what are called " hosi)ital 

 jars," where the live and dead ones are more readily separated. 



The dead eggs are drawn off every day, otherwise they are liable to 

 become loaded with silt from the water and sink, mixing with the live 

 eggs and making it difficult to separate them. 



For the removal of dead eggs from the jars a long-distance siphon is 

 used at Put-in Bay station, which saves much labor. It is constructed 

 thus: To the short end of the ordinary siphon, which consists of a thin 

 quarter-inch brass tube about a foot long bent into the form of a goose 

 neck, is attached a i^iece of common rubber tubing 3 or 4 feet long with 

 a finch interior diameter. This is connected with a rubber tube of the 

 same size and long enough to reach the whole row of jars or all in the 



