, The Irish Nainralist. January, 
that, in fact, it is repelled by the light which so strongly 
attracts the infant worm. (" L. ruber est extr^mement 
sensible a la lumi^re dans le sens negatif ").^ This positive 
phototropism in the young worm, as contrasted with the 
negative phototropism in the adult, probably subserves the 
dissemination of the species by attracting the fry to the 
water surface from the dark stations where it is hatched out 
on the under side of stones. 
It seemed probable that the positive phototropism 
demonstrated for the young Lineus gesserensis might be 
found to extend to the immature stages of other members 
of the Annelida. An opportunity of testing this supposition 
was afforded me on the 20th July last, when I took in 
the Grand Canal, Dublin, a specimen of the fresh -water 
leech, Glossiphonia heteroclita, carrying under its wing, as 
it were, a brood of seventeen young leeches. These were 
all attached to the underside of the parent by their posterior 
suckers, and twined together in a Laocoon-like group. 
The length of each was just i mm., and all had six well 
developed eye -spots disposed in the arrangement charac- 
teristic of the species. By the 29th of July all of the 
juvenile leeches had abandoned the parent and begun to 
fend for themselves. They looped briskly across the bottom 
of the dish after the manner of their order, and some indi- 
viduals climbing the sides launched out on the water surface, 
where a film of mucus enabled them to continue their 
looping progress. These young leeches were subjected to 
a series of experiments similar to those already described 
in the case of the juvenile Lineus gesserensis ; but, contrary 
to expectation, they proved absolutely insensitive to light. 
Repeated exposures failed to elicit any movements either of 
attraction or repulsion. 
Sandycove; Co. Dublin. 
.11 am indebted to Mr. R. Southern for a reference to this paper, which 
is entitled; " Quelques Observations biologiqiies -et Experiences sur la 
Faune des bords de Cuvette. " 
