162 EYES OF MOLLUSCS 



you will kindly attribute it to a similar occult influence on the 

 compiler of this paper, if he has therein proved to you that water 

 can be made (at any rate as the subject of an address) very dry. 



'£;^C':> of nDollu5C6 anb Hvtbropo^^/' 



By Dr. William Patten, of Naples. 



Preparation of Young Peetens from 1-3 mm. long. I. — Mol- 

 luscs. — I. — Specimens are placed in a mixture of equal parts of 

 sublimate and picro-sulphuric acid. After ten or fifteen minutes 

 they are washed in thirty-five per cent, and seventy per cent, of 

 alcohol. 



2. — The shells are then opened and the mantle dissected out 

 with needles. Thus treated, the shape of the mantle is well pre- 

 served, whereas if removed before hardening it becomes much 

 coiled and twisted. 



3. — Each mantle edge may be cut, according to its size and 

 curvature, into three or four pieces, and these will then lie 

 sufficiently straight for convenient sectioning. 



It is necessary to use a different reagent for nearly every part 

 of the eye. 



The Rods.— (Zhxoxmc acid gives the most varied results accord- 

 ing to the strength, time of action, and temperature of the 

 solution, or by various combinations of these three. For instance, 

 one-twentieth to one-fifth per cent, for thirty to forty hours failed 

 to give any conception of the structure of the rods, while other 

 parts of the retina, and of the eye itself, were well preserved ; but 

 when allowed to act for half an hour at a temperature of from 50'' 

 to 55° C, perfectly preserved rods with their nervous net-works 

 are obtained; while, on the other hand, the remaining tissues 

 become so granular and homogeneous as to be unfit for study. 

 This treatment allows the rods to be removed in flakes and their 

 ends examined without the aid of sections. // is only in this way 

 that the axial nerve-loops can. be observed. 



* From 77ic A//icriia?i Naturalist. 



