DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 693 
may enter in this form (No. 89). In osseous fishes a similar condition would appear to 
obtain, one spermatozoon being suflicient ; but as this does not plug up the micropyle, 
others may also enter, indeed, Ransom observed this in Gastrosteus. “I watched closely 
one egg,” he says, “‘ which was placed with the micropyle in full face, so that the aperture 
at its apex was well seen. Spermatozoa approached and entered the funnel, and 
one was watched till it disappeared, apparently in the direction of the interior of the 
egg, Just at the moment when it seemed to occupy the aperture at the apex of the 
micropyle. Immediately after the depth of the funnel began to diminish, and a 
breathing chamber commenced to form; two or three more spermatozoa were, less 
distinctly, seen playing about in the apex of the funnel as it was shortening; one of 
them appeared to become still before it vanished apparently inwards” (No. 127, p. 461). 
The exaggerated length of the micropylar funnel, which Ransom describes in Grastrosteus 
as enabling it to dip into the granular discus proligerus, has not been described in other 
Teleosteans. Neither ANDRE nor GERBE mention it in the trout, nor does His show it 
in the trout or salmon; while in pelagic eggs the micropylar eminence, though distinct, 
is not by any means prominent (PI. I. figs. 11-14). A lengthened micropyle is indeed 
unnecessary, the mere presence of the spermatozoon within the ovum being the 
essential point. The actual entrance of sperms has been seen in very few Tele- 
osteans. Ransom, as already noted, saw them occupying the external orifice of the 
micropyle, and ANDR# speaks of observing a sperm apparently entangled, in the micro- 
pylar canal, by the jutting ends of the radial strize, which appeared to him to serve 
for securing the sperm after its entrance (No. 4, p. 201); but there seems to be no 
column of protoplasm facilitating the passage of the sperm from the micropyle to the 
female pronucleus, such as CaLBERLA describes in Petromyzon planeri. The head of 
the sperm in this form separates from its flagellum, and passes along the proto- 
plasmic column, which withdraws from the micropyle (CALBERLAa’s dussere Mikropyle), 
and the sperm proceeds through the neck of the column (distinguished as the inner 
micropyle) to the enlarged central termination, where the “eikern” or female pro- 
nucleus is seated. Here conjugation of the two pronuclei is effected (No. 38, p. 458, 
Taf. xvii. figs. 5, 6, 7, and 8). Possibly the preformed discus proligerus may repre- 
sent this column; and in those Teleosteans in which no dise is formed, the distance 
between the inner orifice of the micropyle and the protoplasmic cortex of the vitellus 
is insignificant. The spermatozoa of Teleosteans seem to be of the ordinary type, 
and show, so far as observations go, little difference in structure—the usual head 
or enlarged portion being distinguishable from the hair-like tail or flagellum (PI. 1. 
fig. 9). 
Polar Globules.—The details of the phenomena of fertilisation in osseous fishes are 
probably not unlike those in forms more fully known. Horrman has deseribed the 
formation of the pronucleus and ejection of a polar globule in Scorpena, Julis, and 
Crenilabrus, and he states that the globule closes up the orifice of the micropyle, 
and prevents the admission of other sperms after that of the single sperm which 
