57 



with good results, should be made of small bunches of 

 cotton wool, strips of undyed cloth, bunches of bristles, 

 sheets of mica, and similar materials which would afford 

 temporary attachments for the fry and which afterwards 

 could be separated when ready to be remo^^ed to more 

 commodious quarters or artificial nurseries. In order to 

 study the manner in which the frj^ at first fixes itself, it 

 will doubtless be necessary to use cotton wool, thin strips 

 of mica, or glass. It is only by this means that the true 

 character of the attachment can be learned from the ob- 

 jects themselves, brought on to the stage of the micro- 

 scope in an entirely undisturbed condition. Beyond the 

 period of fixation it would probably not be judicious to 

 retain the fry in the hatching boxes, because they are 

 now in a condition to feed actively, and should be placed 

 under such conditions in a supx3ly of constantly changing 

 unfiltered water, as v\^ill suj^piy them with an abundance 

 of food. This brings us to the consideration of 



NUK SERIES. 



These, I apprehend, would best be made in the form 

 of galvanized wire cages, of 8 inch mesh cloth, inside of 

 which a number of trays might be placed one on top of 

 the other. These trays might in fact be made to answer 

 as supports for the collecting apparatus in the hatching 

 boxes, to be afterwards transferred with tlie affixed sj)at 

 to the nursery cages. The greatest care Avould have to 

 be exercised in the care of the very young fry until it 

 was about ten days old from the time of fixation. JN^o 

 noxious animal growths ought to be permitted to grow 

 upon the trays or collecting aj)paratus if it is possible to 

 prevent it, nor should the fry be exposed for any great 

 length of time to the air, which would no doubt be very 

 injurious. The cages if totally immersed should be pro- 

 vided with a wire cloth cover with meshes as fine as 

 those of the sides and bottom in order that carnivorous 

 fishes and mollusks may be effectually excluded. After 



