336 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



pipette after repeated body pressure. Milt may be collected in vessels clean, soiled, 

 or rusted, and will retain its activity (out of water) for at least six minutes. Obtained 

 by excision the milt may be separated from the fragments of cut testes by coarsely 

 straining through cloth. For convenience in handling', it was found that the milt 

 might best be secured and retained in a long rubber-bulbed pipette. 



If untouched by water the eggs remain capable of fertilization for several (five) 

 minutes. Details in' the mode of introducing the milt seem of but little importance. 

 2S"o better results followed the introduction of milt directly from the living fish than 

 of that strained from cut testes and retained several minutes in pipette. A few drops 

 of milt were found to fertilize about 2 liters of eggs. 



In the experiments, running water was in some cases added to the egg mass at 

 the time of fertilization, in others as long as ten minutes afterward; in all cases were 

 results approximately the same. Within from twenty to thirty minutes the eggs have 

 become viscid and " set." 



Under conditions of natural spawning it seems probable that the eggs are fer- 

 tilized at extrusion, since experiment failed to fertilize eggs that had been immersed 

 in water about half a minute. This spawning condition is further attested by the 

 scratches and abrasions noted on the abdomens of spent fish, both male and female. 



Difficulties in sturgeon culture have usually been reduced to three: (1) That of 

 obtaining ripe eggs and milt simultaneously; (2) that of imperfect means of. aeration 

 of eggs, and (3) that of inroads of fungus. It is evident that by careful experimental 

 study the dangers of malaeration and fungous growth might be reduced, if not largely 

 obviated. To these problems the attention of the writer was especially directed. 



Difficulty of aeration. — Sturgeon eggs have proven difficult to -handle on account 

 of their viscid character. Shortly after artificial fertilization the eggs stick together 

 in a glue-like mass; this, speedily hardening, forms a compact egg mass, whose deuse 

 jelly-like matrix the culturist finds does not permit the inner and innermost eggs to be 

 sufficiently aerated. Dying in consequence, these become the cause of the loss of the 

 intimately connected surrounding although better aerated eggs. 



On the natural spawning-grounds this harmful condition does not, apparently, 

 maintain. The eggs, fertilized and becoming viscid, appear to be drawn out into 

 stringy clusters or ribbons, attaching at all points to submerged objects. Sticks, 

 water weeds, fish nets, and especially brush, spread over with a thin layer of sturgeon 

 eggs, are well known to the fishermen. Egg attached objects, moreover, it is generally 

 noted, are found only in deeper, usually channel waters. 



Favorable aeration, as suggested by natural conditions, seems accordingly to be 

 insured by the disposition of the eggs in thin layers and by a plentiful water supply. 

 To imitate these natural hatching conditions in a way practicable for large numbers 

 of eggs is clearly the bourne of the culturist. To attain this end, however, is not his 

 easiest task. The eggs, becoming viscid speedily, must be attached to the hatching 

 devices with the greatest promptness. The hatching trays must be prepared for 

 immediate use, and the eggs must simultaneously be spread over them in a single 

 layer. Otherwise, all eggs becoming " set" at the same moment, those that remain 

 uuspread must, in their clustered condition, be inevitably lost. 



Aeration seems to be especially concerned with three cultural details: (1) The 

 character of the egg trays; (2) the mode of egg attachment, and (3) the means of 

 securing water circulation. 





