THE EYE OF PECTEN. 
455 
generally cling to it. For examining the isolated rods of the 
retina I have allowed the eyes to remain in a solution of 
chloral hydrate for four or five days. I have then dissected 
out the retina with needles as carefully as possible, and 
poured a drop or two of heematoxylin on to the slide. When 
the retina had been standing in hsematoxylin in this manner 
for some hours it was washed with water, teased out with 
fine needles, and mounted in glycerine. 
