6 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
The phototaxis of the Nauplius of Balanus has been examined by 
Loeb, and Loeb and Groom, and Loeb! states that they are positively 
heliotropic upon leaving the egg, but soon become negatively heliotropic. 
This I consider is entirely due to over-stimulation by the light, for on 
keeping for some time in darkness the negative organisms become strongly 
positive to the same intensity of light in which they were previously 
negative, and in which part of them left during the same interval have 
continued negative. The statement of Loeb and Groom that they remain 
positive in artificial light (gas flame) is confirmed by the results of my 
experiments, but holds up to a certain intensity of illumination only, 
for if the hght of a small lamp was converged by means of a cylindrical 
museum jar in which the organisms were contained, the organisms in the 
strongly illuminated area gradually became negative and passed into the 
shaded parts or to the distal pole. 
In later experiments made at Berkeley, U.S.A., Loeb found that 
Nauplii there behaved differently from those examined in his earlier 
experiments made at Naples, and showed more complicated reactions. 
Working with the larvae of Polygordius, and with those of Limulus, 
Loeb noticed a phenomenon which was also conspicuous throughout the 
present series of experiments, namely, that the positively phototactic 
organisms gathered in a group towards the top of the vessel, while the 
negative organisms at the same time as they gathered away from the light 
congregated at the lower part of the vessel near the bottom. 
This I have also invariably observed when a tow-netting is brought 
into the Station and placed in the diffuse light of a window in a glass jar. 
The positive organisms are in a compact group nearest to the window, and 
almost ai the surface of the water; while the negative ones are at the most 
distal point of the jar from the window and down near, or on, the bottom. 
The same arrangement holds even in a shallow dish, well illuminated 
throughout its depth, the positive organisms are up close to the surface, 
and the negative ones on the bottom of the dish. ‘The arrangement 
continues when the organisms are lit in the dark room by a candle on the 
same level as the water—still the positive ones are near the surface and 
the negative ones near the bottom. 
1, Loc. cit, 
