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served, in different ways, by Salvatore Lo'Bianco. For this, and 
many other services, it is a pleasant duty to return Prof. DoHRN 
my most sincere and grateful thanks. 
Myxine I have had in abundance from the neiglibourhood of 
Bergen (Alverstrommen). 
3. Methods of Investigation. 
If my researches, in several respects, contribute somewhat to 
advance our knowledge of the minute structure of the nervous ele- 
ments, as I hope they will, and although I, in several respects, have 
arrived at results very different from most other writers, I think 
that must principally be ascribed to my methods of investigation, and 
especially to the methods employed for fixing, hardening, and staining. 
I have employed fresh isolated preparations, as well as macera- 
tions and sections. 
The fresh preparations were, usually, either examined in larger 
pieces (commissures or nerves) in the blood of the animal as re- 
commended by Freud (1882) or they were made in this way; 
the structures (nerves or ganglia), were tåken as rapidly as possible 
from the living animal, and then by help of fine needles •) were 
teased in the blood of the animal, and afterwards examined as quickly 
as possible. Very often, also, I took as thin sections as possible 
from the fresh animal, examined them in blood, or teased and 
isolated the elements from them, by help of needles, in the same 
fluid. The last method is especially to be recommended for such 
Molluscs, e. g. Patella, as have the pedal nerve-cords and nerves 
imbedded in the strong muscular mass. A perfect isolation is, 
however, as a rule, not possible in this way, and therefore macera- 
tion becomes necessary. 
The fluid recommended by B. HALLER is not bad for the purpose. 
It consists of a mixture, acetic acid 5 parts, glycerin 5 parts. Aqua dest. 
^) For this purpose I would especially recommend glass-needles, which are, 
I believe, originally recommended by Stricker. They are deaner, smoother and, 
in several respects, hetter than any metal-needles. They are, certainly, easily broken, 
but they are, also, on the other hand, very easily made from a glass-rod, with the 
aid of a gas-jet. If the hairlike extremity of the needle is passed through the 
flame before iise, a very good point is obtained, blimt enough not to break or cut 
the elements when cautiously isolated, but still very fine and pointed, allowing the 
most delicate manipulation. 
