HATCHING-HOUSES AND APPARATUS. 47 



allows slight, lateral motion if required, and bind- 

 ing them together allows a shock to "be distributed 

 over the entire set. The force of a blow which 

 would cause breakage of a single tube is thus 

 divided over a number, and they escape un- 

 harmed. The ends of the frame are fastened with 

 screws, and, should any of the glasses become 

 broken, they may be readily removed and others 

 substituted. A single tray, or, at most, a pair, 

 are all that are required for experimental pur- 

 poses ; they may be supplied with water from any 

 bath-room, and have, as an adjunct to the aqua- 

 rium, met with great favor from persons interested 

 in natural history or physiology The shell of the 

 egg being transparent, the young, at all periods 

 of its development, is plainly seen. We were, as 

 far as we can ascertain, the first to introduce this 

 beautiful piece of fish apparatus into America, 

 and met with some opposition from those who 

 were wedded to their gravel troughs. We desired 

 to select a location as unfavorable as possible for 

 fish-hatching, and finally decided upon the lect- 

 ure-table in the laboratory of the University of 

 Pennsylvania, during the height of the lecture 

 Reason ; yet, amid this atmosphere, contaminated 

 by all the noxious gases which the ingenuity of 

 man can eliminate, many of which are highly sol- 

 uable in water, exposed to great variations of tern- 



