18 



Journal of Applied Microscopy. 



A Method of Preserving the Eye for 

 Sectioning, or for Demonstrating 

 the Area of Acute Vision. 



James Rollin Slonaker, Ph. D., 

 Instructor in Zoology, Indiana University. 



In order that the eye may be well 

 preserved it must be placed, as soon as 

 possible after death, in Perenyi's fluid. 



10 per cent Nitric acid, 4 parts. 



95 per cent, alcohol, 3 parts. 



0.5 per cent. Chromic acid, 3 parts. 



The eye should be carefully oriented 

 before removing from the head by sew- 

 ing- a tag to the outer layers of the 

 sclerotic, so that the orientation may af- 

 terwards be exact. In removing the ball 

 it should not be punctured, for this in- 

 variably causes wrinkling of the retina. 

 As much as possible of the fat and mus- 

 cle should be removed before immersing 

 it in the Perenyi. The bulk of the pre- 

 serving fluid should be ten or fifteen 

 times the size of the eye. 



The time that the Perenyi should be 

 allowed to act depends on the size of the 

 eye and the nature of the sclerotic. Small 

 eyes, as rat, sparrow, etc., are usually 

 left in 24 hours and large ones, such as 

 cow, horse, or those in which the sclero- 

 tic contains bony plates, 36 to 48 hours 

 are required. A good deal of latitude 

 may be taken, however, regarding the 

 time. 



After the action of Perenyi's fluid the 

 eye is carried up through the following 

 grades of alcohol, leaving it 24 hours in 

 each: 70 per cent., 80 per cent., 90 per 

 cent., 95 per cent., 100 per cent., and 

 finally a mixture of equal parts of 

 absolute alco'hol and ether. It is 

 then well hardened and ready for 

 celloidin imbedding. Before putting 

 into celloidin a window is cut in the 

 same plane as the desired sections ex- 

 posing the hardened vitreous humor. Af- 

 ter this is carefully removed without in- 

 jui'y to the remaining structures, the hol- 

 low ball is put into celloidin. I have 

 used three grades of celloidin, ranging 

 from very thin to very thick, and have 

 left the eye at least 48 hours in each. It 

 can remain longer with better results. 

 It is then mounted on a block in the 

 usual manner and cut in 80 per cent, 

 alcohol. 



I have not succeeded in securing good 

 sections of the whole eye by imbedding 

 in paraffin, since the lens becomes 

 almost flinty and prevents sectioning. 



If one desires only to demonstrate the 

 fovea and not to make sections, the front 

 half of the eye may be cut off after 

 passing through the 80 per cent., but pre- 

 ferably after 95 per cent, alcohol. When 

 thus removed, together with the vitreous 

 humor, the retina is seen spreading 



smoothly over the posterior half of the 

 ball and the fovea, if present, and the 

 optic papilla may be easily seen. Such 

 demonstration material can be kept per- 

 manently in 80 per cent, alcohol. 



This method applies only in a gross 

 study and can not be used successfully 

 for the minute structures of the retinal 

 elements. If such is desired the Golgi 

 method as used by Ramon y Cajal (t), 

 or the "Methyl Blue" method (t) will ad- 

 mirably serve the purpose. 



t Ramon y Cajal. Retina der Wirbelthleren. 

 Uebersetzt und herausgegeben von Richard 

 GreefC. 



t A. Dog'lel. Ueber das Verhalten der ner- 

 vosen Elemente In der Retina der Ganoiden, 

 Reptlllen, Vogel, und Saugethiere. Arch. f. 

 mik. Anat. Bd. xli. 



DISCUSSION. 



Papers upon live subjects within the province of 

 the Journal will be printed over the author's 

 signature. 



Photography in the Biological 

 Laboratory. 



W. H. MUNSON. 



Workers in all lines are earnestly seek- 

 ing short cuts to flnal results, and among 

 these none are more earnest in their 

 endeavors than are biologists; and espe- 

 cially they who have diversified work in 

 this subject, or are hampered by the 

 necessity of devoting much time to oth- 

 er subjects. 



Many such an one, overworked during 

 the year, has put in a part or all of the 

 summer vacation in studying nature 

 from the standpoint of the artist, hav- 

 ing as his constant companion the inev- 

 itable hand camera of some sort or oth- 

 er. If he has gotten the most pleasure 

 and profit possible in his study, he has 

 developed and printed his own pictures, 

 thus, in a large measure, preparing him- 

 self for a kind of work that may be 

 made to facilitate his own efforts, and 

 largely increase the interest and profit 

 of his pupils. If, instead of being a 

 teacher in a high school this particular 

 camera-fiend is in charge of college 

 classes in general biology, in zoology, 

 or in botany, he can still make very good 

 use of his acquired skill in photography. 

 If he is largely engaged in research on 

 cytological lines, the skill becomes al- 

 most a necessity to him; and he must 

 acquire it sooner or later, if his hand 

 camera work has not already initiated 

 him into the mysteries of the art. 



The specialist in higher lines already 

 knows the full value of the process in 

 his work, and may not be in any way 

 helped by anything the writer may be 

 able to say on the subject; and we there- 



