260 JOURNAL OF COMPARATIVE NEUROLOGY. 
The work on the marine forms was done at the Hopkins’ 
Seaside Laboratory, Pacific Grove. 
A simple muscle-nerve preparation suitable to the graphic 
method is not obtainable in the worms. The preparation we 
employed consisted of the ventral nerve-cord in connection with 
an anterior or a posterior part of the worm serving as a reacting 
portion. This may be called a muscle-nerve-cord preparation 
to distinguish it from the simple muscle-nerve preparation. 
The length of the nerve-cord obtainable for this preparation is 
considerable in some members of the group, and the muscle 
part, especially if prepared from the anterior end of the animal, 
is strong enough to raise a light lever. The extreme posterior 
end of the worm can be used for a reacting portion in few forms 
only, owing to its greater fragility. The length of the reacting 
portion can be suited to any case; we found a length that gave 
a height of contraction of 10 to 20 mm. as magnified by the 
lever most convenient, but in worms with well developed chit- 
enoid epidermis a less height of contraction had to suffice. . 
The apparatus used in the present work was much the same 
as that used by us in the work on the determination of the rate of 
impulse in molluscs (17, 1903). Many difficulties were en- 
countered in preparing the worms for experimentation, but af- 
ter many unsuccessful attempts the following method was found 
most serviceable. The animal was securely fixed by dissecting 
needles, ventral side down, to the moveable floor of a large 
moist chamber supported on a universal stand, the point of fix- 
ation being sufficiently posterior or anterior to give the desired 
length of the reacting portion. In case it was desired to 
prepare the reacting portion from the anterior part of the ani- 
mal the extreme posterior end was then secured in the same 
manner, care being taken that the anterior and posterior points 
of fixation were so close together that maximal longitudinal 
contraction of the worm between these two points exerted lit- 
JOHNSON (Preliminary Account of the Facific Coast Annelids, Prec. Cal. Acad. 
Sci., 3rd ser. Vol. I, No. 5, 1897; the Polychaeta of the Puget Sound Region, 
Proc. Bost. Soc. Nat. Hist., Vol. 29, No. 18, 1901); and the species not named 
are now in his hands for study. 
