I9i6. CoiyGAN. — Photolropism and Eye- Spots in Linens. 7 
OBSERVATIONS ON PHOTOTROPISM 
AND THE DEVELOPMENT OF EYE-SPOTS 
IN THE MARINE NEMERTINE, 
LINEUS GESSERENSIS.^ 
BY NATHANIEL COLGAN, M.R.I. A. 
While shore -collecting near Bullock Harbour, Dublin Bay, 
on the 26th April last I found attached to stones near low 
water mark several gelatinous egg -masses, apparently the 
spawn of some marine annelid. One of the largest of these 
masses, about an inch and a half in length, was taken home, 
and on examination and comparison with the plates of 
Mcintosh's " Monograph of the British Annelids " was 
found to closely resemble the spawn of the Nemertine 
Lineus gesserensis (Miiller). The egg -mass, or " mucus 
chord," as Mcintosh terms it, was roughly sausage -shaped, 
the creamy ova being distributed through the transparent 
mucus in two irregular longitudinal bands quite visible to 
the naked eye. Under a low power the apparently simple 
ova were resolved into diaphanous, flask-shaped capsules 
containing from three to five eggs each. Development was 
already far advanced, and on the 2nd May, just six days 
after the removal of the egg-mass from the shore, the first 
of the young worms emerged from its capsule and pushing 
its way through the general mucus envelope began to travel 
rapidly along the bottom of the glass dish. The close 
resemblance of this infant worm to figure 9 of Plate xxiii 
of the " Monograph," taken along with the equally close 
correspondence of the egg-capsules with figure 6 of the 
same plate put beyond all doubt the identity of the worm 
with Miiller's Lineus gesserensis, a species common all round 
our shores. 
The young Lineus, just 1.5 mm. in length was remarkably 
active. It moved backwards and forwards with equal 
ease and rapidity, and, mounting the side of the glass disli, 
launched out on the surface of the sea water where it floated 
' I have used throughout these notes the name adopted by Mcintosh 
in his "Monograph," though the synonym L. ruber has of late years 
.?uperseded it. 
