1G6 TWO NEW INSTRUMENTS FOR BIOLOGISTS, 



fluids and the eggs are therefore subjected to the action of those 

 fluids under normal conditions. The capsule is recovered from 

 the iseces in the case of man but in any way desired in the case of 

 lower animals. The results leave little room for the distressinsr 

 uncertainties often attendant upon simply feeding the eggs. On 

 recovery the contents of the capsule are invariably acid. The 

 inserted eggs are therefore subjected to the action of the gastric 

 fluids only. 



The eggs experimented upon are put into the capsule either 

 through the aperture shown at u, Fig. 6, before it is stopped 

 with glue, or are introduced through t after u has been stopped. 

 In this latter case ?(- may be made so small that no resulting 

 embryo can escape, a result which may also be secured by tying 

 filter paper over the aperture u by means of cloth and a strong 

 fine thread. A. pipette may be made with an exceedingly fine 

 capillary neck longer than the distance from u to r, Fig. 6, and by 

 means of this pipette eggs (in wattjr) insei-ted into the capsule 

 through t after u has been stopped. Fusing the capillary part 

 t does not heat the capsule sufficiently to injure living eggs. 



There is a choice of ways in exhausting the air. One may attach 

 a rubber tube at r and by sucking ones utmost thereon produce a 

 sufficient exhaustion. I use a pair of two-quart bottles containing 

 water and connected by a long piece of rubber tubing arranged so 

 that by lowering or raising one of the bottles by means of a cord and 

 pulley a variable pressure or suction can be exerted at will. I have 

 not found it expedient to reduce the pressure in the suction-cap- 

 sule to less than three-quarters of an atmosphere, an effect which 

 one can barely produce with no other pump than one's ow'n lungs. 



Capsules varying from 1 millimetre to 4 millimetres may be 

 easily fed to many animals and a little ingenuity will succeed in 

 introducing them almost anywhere desired. I have repeatedly 

 swallowed such capsules and have never experienced any inconve- 

 nience beyond a nervous anxiety at the first trial. 



As a small proof of the usefulness of both the instruments here 

 described, I accompany this paper by another entitled, " Oxyuris- 

 larvse hatched in the human stomach under normal conditions." 



