Mat 17, 1907] 



SCIENCE 



783 



Notes on the Behavior of Sea- Anemones: 



Chas. W. Hargitt. 



The paper discussed the aspects of be- 

 havior of several species of sea-anemones 

 ■studied both under natural conditions and 

 those of the laboratory. The points chiefly 

 under observation had reference to the be- 

 havior of these creatures under the influ- 

 ence of light. So far as known few details 

 along this line have been recorded. 



At least three species of anemones were 

 found which showed very evident reac- 

 tions to photic stimuli, namely, Eloactis 

 '£Halcampa) producta, Sagartia modesta 

 and S. leucolena. Of these two are tube- 

 dwelling, burrowing in the sand near tide 

 lines, and forming rude tubes or burrows 

 through the adhesive secretions of the ecto- 

 derm. S. leucolena is occasionally found 

 in similar habitat, though chiefly adhering 

 to rocks or among colonies of ascidians, 

 or sponges, on piles of docks, etc. Experi- 

 ments showed that the first two species are 

 most sharply responsive to light, and this 

 sensory sense is located chiefly in the ten- 

 tacles and oral regions of the body. S. 

 leiocolena, while less sensitive, is yet evi- 

 dently so in strong light. Exposed to 

 direct sunlight it quickly closes up into a 

 hemispherical mass, or creeps over the edge 

 of the rock or shell into shaded portions, 

 of the aquarium. In its native haunts it 

 may be found protruding its crown of 

 tentacles from a crevice while the body is 

 hidden. 



Sagartia lucice is a free-living species 

 found abundantly almost everywhere, on 

 rocks in open pools, or on floating fucus, 

 and freely exposed to direct sunlight, ac- 

 tion of waves, etc. Of similar habit is 

 Metridium marginatwm. Neither of these 

 species seems in the least degree responsive 

 to photic stimuli. Under a strong beam of 

 ■sunlight reflected directly upon them for 

 ten minutes they showed no response what- 

 ever. 



These facts, together with others as to 

 food-habits, etc., render it quite certain 

 that their behavior is due to several factors, 

 and that in response to light there is an 

 evidence of adaptation involving varying 

 physiological conditions, of which the bur- 

 rowing habit is one of several expressions. 

 The Simulation of Death iy Fishes: 

 Ulric Dahlgren, Princeton University. 

 Spawning Behavior and Sexual Dimorph- 

 ism in Fundtdus heteroclitus and Allied 

 Fish: H. H. Newman, University of 

 Michigan. 



Some Points in the Development of the 



Florida Alligator: AiiBeet M. Reese, 



Syracuse University. 

 External Morphology of the Head of 



Limulu^: "William Patten, Dartmouth 



College. 



The Function of the Gastrolith of the 



Lobster: L. "W. Williams, Harvard 



Medical School. 



The gastrolith appears for the first time 

 in the fourth stage lobster at or before the 

 middle of the period between the molts 

 and, after the molt, there proceeds, pari 

 passu with the dissolution of the gastrolith, 

 a hardening of the gastric teeth, the 

 mandibles, and the chelipeds. Soon after 

 the absorption of the gastrolith the newly 

 molted lobster attacks and eats the greater 

 portion of its cast. Reasoning from these 

 facts, we suggest that the lime in the 

 gastroliths is reserved for the rapid 

 hardening of the teeth, mandibles and 

 chelipeds so that the relatively vast supply 

 of lime in the slough and in other shells 

 may be made available, at once, for the 

 hardening of the new shell. 



This paper is to appear in the Report 

 of the Rhode Island Commission of Inland 

 Fisheries, now going to press. 



The Artificial Production of a Single Me- 

 dian Eye in the Fish Embryo by Means 



