396 S. J. HOLMES 



Both papers by Hachet-Souplet ^' deal with the practical 

 methods employed in the formation of associations in the animal 

 mind. 



Hargitt " describes the explosive discharge in rapid succes- 

 sion of the sex products of a number of specimens kept in an 

 aquarium. It remains a question whether the sex products 

 matured so nearly at the same time that they were all dis- 

 charged within thirty or forty minutes, or whether the dis- 

 charge of one individual afforded a stimulus which evoked the 

 discharge in the others. Similar observations are cited in 

 other species. 



Herbst ** shows that the heteromorphic antennule which is 

 regenerated in the place of an eye in Palinurus and Palaemon 

 reacts to mechanical and chemical stimuli in a manner quite 

 different from the response of the normal antennule. In many 

 respects the reactions are like those elicited by the stimulation 

 of the optic peduncle, the differences being perhaps due to the 

 difference in structure and musculature of the two organs. The 

 experiment is of especial interest in relation to the doctrine 

 of the specific energies of the nervous system. 



Hess's paper ^^ contains numerous observations on special 

 features of the light reactions of both vertebrates and inver- 

 tebrates. It is mainly devoted to a consideration of the 

 effects of light of different wave-lengths on the movements 

 of animals. Experiments were carried out upon several species 

 of caterpillars, Daphnia, Podopsis, and Atylus among Crustacea, 

 Culex, Musca, Coccinella, and other insects; Sepia, Eledone, 

 and several eyejess bivalves among the mollusks, and Amphioxus. 

 The general conclusion reached is that all these forms are most 

 affected by the green or yellowish green rays. Judging from 

 their behavior, the curve of brightness of the spectrum is the 

 same for these animals as for color-blind human beings. 



Specimens of Euhranchipus ornatus sp. no v. were found by 

 Holmes ^' to be strongly positive to light from a narrow source 

 such as an incandescent light in a dark room, although they 

 manifested no marked reaction to diffused light coming through 

 a window. If illuminated from below, Eubranchipus swims 

 ventral side downward, instead of in its usual position on its back. 

 Two different methods of orientation are employed, according 



