62 
Transactions of the Royal Mieroseopical Society, 
was thrown forward so as to form a loop, in the area of which a 
most deHcate membrane was seen to be adherent to the zoic 
filament. The end of the tail, however, was always free. 
Several matters of interest were observed — the structure of the 
spermatic particles, the dimensions of their parts, and the length of 
the filaments. 
The total length of each spermatozoon was of an inch. It 
begins at the moderately acute point of an elongated conical head 
of an inch in length by -g^yV^ of an inch in thickness ; behind 
which the body, slightly more attenuate, ended almost into the 
vague. The " head " presented a small curve ; but the body lay 
straight at times, or else threw itself into serpentine flexuosities. 
A Tolles' recent yV immersion objective with that maker's i-inch 
ocular displayed many new points. The head, highly refractive 
and firmer than the other part, appeared to consist of a lamina of 
homogeneous substance bent along its axis, the two tumid edges of 
which met on the ventral side. Anteriorly these edges were sud- 
denly bevelled away, and were lost by continuity in a dehcate 
filament ending in a faint swelling. 
Posteriorly the edges contracted at the junction with the body, 
but were seen to be continuous with two cords which had the same 
relation as their originals in the head. They lay close together, 
and from them sprang the dorsal arch, along the ridge of which the 
propelling membrane was attached. 
This delicate film extended like a ruffle from the posterior 
extremity of the head as far as the caudal point ; the main part 
was, however, invisible, but not so the margin, which was bordered 
with a thickened hem. 
In a dry preparation the spermatozoids and their details were 
somewhat deformed, distorted, and spread out ; still the character- 
istics of Amphiuma's seminal particles were very manifest when 
studied with a fine objective. Thus the edges of the cephalic folds 
and the somatic cords assumed a beaded appearance, as did also the 
collapsed arch-fold of the back along its margin. Yet the eye was 
not satisfied with the dried potential male elements, and reverted 
with continually renewed pleasure to the moving zooids. 
But the charm of the whole study lay in the movements of 
these things, which advanced whether the tail swayed with a lashing 
motion or formed a straight line. From the junction of the head with 
the body to the extremity of the tail the double filament appeared 
encircled with the thread of a most delicate spiral, which seemed 
to wind from the head towards the caudal termination. And this 
direction was maintained so long as the zooid was free ; but, what 
was indeed wonderful, the motion of the spiral was instantly reversed 
as soon as the head became attached or entangled, although 
the lashing or swaying motion continued if it had been executed 
