EFFECTS OF RADIANT ENERGY ON THE EYE. 661 



not to rupture the capsule, and the lens removed and placed in Zenker's 

 fluid for two hours. The lens may be fixed in situ and removed after- 

 wards, but this causes the iris epithelium to adhere to it. Birch- 

 Hirschfeld mistakenly regarded such adhesions, which he found in 

 the exposed eyes, as pathological. They may be removed by gently 

 rubbing the capsule with wet filter paper. The lens is now rinsed 

 in water and the capsule incised all around the equator with a sharp 

 knife. The anterior capsule is now readily stripped off, floated in 

 water and treated as follows: Lugol's solution (1%) a few seconds. 

 Water. 95% Alcohol two minutes or longer. Water. 10% aque- 

 ous solution sodium hyposulphite until color of iodine is removed. 

 Water. The capsule will be found to curl toward the cell free side. 

 It is now floated upon a piece of paper and by means of scissors five 

 radial incisions are made through both paper and capsule reaching 

 to within a short distance of the centre. It is then freed from the 

 paper and floated upon a cover glass with the curled edges up, so that 

 the epithelium is in contact with the glass and thus will be nearest 

 the lens of the microscope. The curled edges are flattened out by 

 stroking with bits of filter paper, which removes the excess of water 

 and prevents the edges curling again. The preparation is now blotted 

 firmly with filter paper. Alum hematoxylin until deeply stained. 

 It is best to use a sharply acting hematoxylin solution and avoid differ- 

 entiating in acid alcohol as the latter is apt to act unevenly. Water. 

 0.2% solution of water soluble eosin in 80% alcohol, 30 minutes. 

 W^ater. The preparation is now thoroughly dehydrated in absolute 

 alcohol, cleared in oil of origanum followed by xylol, blotted again if 

 necessary, and mounted on a slide in xylol-balsam. 



Retina: Vertical sections of the retina 6 /x to 8 /u in thickness, 

 were made in all cases. These always included the optic disc and the 

 area below it that had been exposed to the light during the experiment. 

 This area contains a much larger proportion of ganglion cells than any 

 other part of the retina and may be regarded as analogous to the 

 human macula, although it is much larger and less sharply defined. 

 The ganglion cells are similar to those of the human macula, but never 

 occur in more than a single row. Plane sections of the retina were also 

 often made, and these were found to give the best demonstration of 

 the ganglion cells. 



Sections were always stained in eosin and thionin, which is proba- 

 bly the most satisfactory method for demonstrating Nissl bodies 

 and at the same time gives a beautiful general stain of the retina. 

 Dilute aqueous solutions of thionin rapidly lose in staining power, so 

 that it is important that they be always freshly prepared. The fol- 



