TECHNIQUE OF EYE DISSECTIONS 



THE CKYSTALLINE LENS 



If the preceding dissections have been done, 

 the crystalline lens will already have received 

 some notice. To study the lens properly one 

 should use an eye that has not been hardened 

 and also an eye or the lens of an eye that has 

 been in a 5 per cent, solution of formaldehyde 

 for about two weeks. 



The lens in the unhardened eye will prove 

 too friable to permit much handling. The dis- 

 section should be made, however, in order to 

 give opportunity to notice the crystalline clear- 

 ness of the lens substance, its great magnify- 

 ing power, its attachments, its capsule, etc. 

 For this purpose it is necessary to proceed 

 only as in the dissection for the "hyaloid mem- 

 brane, etc/' That is, use an eye that has been 

 kept in a cool place for several days, and then 

 open it, and remove hyaloid, vitreous, and lens 

 intact, as in the first dissection taken up in 

 this book. To examine the specimen in de- 

 tail, turn it so the lens will be uppermost. 

 (Fig. 18.) 



To remove the lens it is necessary to sepa- 

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