For microscopical purposes and best results it is necessary to 

 obtain the eye fresh, at least not later than an hour after death, 

 and subject it to the action of certain hardening liquids which 

 will permeate and preserve without causing the retina to swell 

 and become wrinkled. With some animals it is quite easy to 

 preserve the retina without its becoming wrinkled or floated 

 off' (fishes, amphibians, reptiles, and some mammals), while 

 with others (most mammals and birds) it is a more difficult task. 



In order to prevent this folding and floating off of the retina. 

 the eye is injected under pressure and immersed at the same 

 time in a bath of hardening fluid. It is carried thus on up 

 through the different percentages of alcohol and imbedded in 





A more minute de- 

 scription of the method 

 is as follows: Fig. 1 

 represents a rack with 

 movable shelves, o n 

 which are placed bot- 

 tles A and A', contain- 

 ing the same fluid as 

 bottles B and B', and 

 provided with siphons 

 to connect with glass 

 cannulas. 



In order to insert the 

 cannula, a hole is care- 

 fully drilled about the 

 equator and on a merid- 

 ian perpendicular to the 

 plane in which it is de- 

 sirable to obtain sec- 

 tions. The perforation 

 is stretched open, rather 

 than cut, so the sclero- 

 tic will clasp the neck 

 of the cannula tightly. 

 A convenient instru- 

 ment for this operation 

 is a spear-pointed dis- 

 secting needle, and not 



