1889.] MICROSCOPICAL JOURNAL. 243 



examined is placed. At a short distance from this glass plate runs the 

 bi"ass rim, c, c, c, seven millimetres high, which, by a proper inclina- 

 tion, conveys the irrigating fluid as it flows off' the organ to the tubes, 

 d^ (/, to which are attached rubber tubes leading to a vessel for receiv- 

 ing the waste fluid. The supports, /, are for holding the irrigating 

 canulae, g. They are pivoted to the plate, and move around a perpen- 

 dicular axis. To the upper end is attached a short brass tube, split 

 along its upper surface, which is tightened by a small thumb-screw. 

 This is connected with the support by a hinged ioint, allowing it to 

 move on a horizontal axis. In this tube is placed the irrigating canula, 

 g. One end of these canulte is drawn out into capillary tubes, and 

 various curves given them in order to meet the requirements of the vari- 

 ous organs used. The tongue and mesentery plates are provided with 

 two of the above-described supports. This is to allow of the use of 

 two canulae, one for irrigating the under and the other the upper sur- 

 face of the organ. At e is a perpendicular rod for supporting the ring 

 for holding the cover-glass. At each side of the plates [in the tongue- 

 plate it is at the end] is a notched support, k^ for holding the rubber 

 tube attached to the canulte introduced into the various organs for infla- 

 tion, etc. Between the rim, c, c, c, and the glass plate. B, bits of cork 

 are wedged for pinning out the organs. 



For examining the circulation in the mesentery, male frogs are to be 

 used so that the examiner may not be embarrassed with the ovaries. 

 An incision is made through the skin on the side of the animal, from 

 the pelvis nearl}^ to the axilla. After all hemorrhage has ceased, the 

 abdominal cavity is opened into by an incision from lo to 20 millime- 

 tres in length. The animal is then placed on the frog-plate, and a coil 

 of intestine is carefully drawn out with a pair of forceps over the glass 

 plate so that it will fall upon the bits of cork, to which it is pinned, leav- 

 ing the mesentery spread out on the glass plate. 



The bladder requires care in its preparation on account of the thin- 

 ness of its wall. A glass canula, B, Fig. 8, is filled with a |"o solution 

 of sodium chloride, and the rubber tube attached to the straight end 

 is closed by inserting a bit of glass rod. The canula is now inserted 

 into the cloaca, and the curved end directed forward into the bladder ; 

 it is held in place by a thread passed through the skin over the sacrum 

 and tied around the canula. An incision, similar to that for the mes- 

 entery, is made in the side of the animal. The glass rod is removed 

 from the end of the rubber tube, the latter raised slightly, so as the 

 fluid will flow into the bladder, distending it. The animal is now 

 placed on the frog-plate, and by gentle manipulation with the handle 

 of a scalpel the bladder is brought upon the glass plate and further 

 distended if necessary ; the glass rod is now replaced in the end of the 

 rubber tube and the latter fixed in the support, k^ Fig. 7. 



The lung is prepared for examination by inserting the canula. A. 

 Fig. 8, into the glottis of the frog. It is held in position by a thread 

 passed through the skin of the nose and tied around the constriction 

 of the canula. An incision carried well into the axilla is made through 

 the skin on the side of the animal, care being taken not to wound anv 

 of the large vessels. The thoracic cavity is then opened by an incision 

 carried well down the side of the animal. The animal is now placed 

 on the frog-plate and the lung distended by gently blowing through the 



