55 



ran tlie slightest risk of losing a single egg from leakage, 

 it occurred to me that the proper thing to do would be to 

 construct a box in which the water passed through a 

 membrane of blotting or filtering paper into the hatching 

 chamber and out of this again through a similar mem- 

 brane into another chamber and allowed to escape. In 

 some such way it will be possible to hatch the minutest 

 eggs and watch the reproduction, division, etc., of the 

 Tery minutest monads. The idea is possibly one of im- 

 mense practical value in oyster-culture and opens up a 

 field of work in embryology in the pursuit of which many 

 conquests are still to be made. 



Another form of apparatus which suggested itself to 

 me during my experiments vrith the device just described, 

 has the advantage of being easily ojjerated by some sim- 

 ple form of pump, by means of which the water may be 

 constantly renewed in the hatching chamber. A metal 

 ring with a bibulous membrane on either face, made 

 water-tight around the edges of the ring, so as to enclose 

 a space into which a short ]3iece of tubing may be screwed 

 at one side and connected with a pump by a rubber tube. 

 In this way, by pumping, water would be drawn into the 

 space included by the ring and membranes, provided 

 these were immersed in the water contained in the hatch- 

 ing chamber. Of course, the membranes would have to 

 be strengthened both inside and outside by a single 

 thickness of stout canvas, the same as I used in makino: 

 my exi^erimental boxes, so as to have the bibulous mem- 

 brane between the sheets of canvas to avoid rupturing 

 the former, by pressure or a(;cident. The diameter of 

 the ring and membranes might be six inches, as more 

 than that would probably render the membranes liable to 

 collapse when the x)^^inp was in operation. The amounf" 

 of water passing through the apparatus I should think 

 would not need to be more than what would completely 

 change the Avatc^r in the hatching chamber once in every 

 half or one hour, so that the inuu]) necessary would be 



