l6o fournal of Comparative Neurology and Psychology. 



under which the present work was done made it practically im- 

 possible to carry out a thorough and complete investigation of 

 the phototaxis of the embryos, so that in several particulars 

 my results are incomplete. For this reason it seems preferable 

 not to publish my observations in detail at this time. For the 

 sake of indicating the general trend of the results as far as they 

 go I will briefly summarize them. I was unable to get any 

 evidence that the first reaction to light to appear after hatching 

 was positive in sense. On the contrary it was clearly negative, 

 regardless of whether the embryos were swimming or walking. 

 Later there appeared a strongly marked positive reaction shown 

 only by relatively few individuals. These individuals when re- 

 sponding in the positive sense to the direction of the incident 

 light were, so far as my observations went, always swimming in 

 a very violent manner. In the same dish at the same time, 

 with all the embryos of approximately the same age, many in- 

 dividuals were negatively phototactic, fewer positively photo- 

 tactic, and still fewer apparently indifferent to light. This ap- 

 plies to light of the intensity of diffuse sunlight. The negative 

 phototaxis is apparently associated with a strong positive thig- 

 motactic tendency. 



It seems very desirable that the reactions of Lvnulus to 

 photic stimuli in any or all stages of its development be thor- 

 oughly investigated under proper conditions for experimenta- 

 tion. I know of no form which seems likely to give more in- 

 teresting and significant results in this field than this organism. 



Discussion of Results. 



With the detailed results now in hand it is possible to 

 make a direct comparison between the behavior of Liimilus in 

 its earliest larval stages and in the adult condition. In order 

 make the comparison easy of comprehension the following 

 table has been arranged. In parallel columns are stated the 

 conditions with respect to certain definite features of the be- 

 havior in the two stages of the life history. 



