Washburn, Comparative Psychology. 513 



observed by Bohn. The actinian first responds to the stimulus of loss of oxygen 

 or drying; then, by anticipation, to a stimulus which regularly precedes this 

 (diminished agitation of the water), and finally to an internal, periodically occur- 

 ring stimulus (28). In paper number 8 of the bibliography, Bohn gives a further 

 account of the persistence of the tidal rhythm in Actinia. The specimens observed 

 by him spontaneously opened and closed in the laboratory for two ot three days. 

 That the rhythm still existed after this time was revealed by the following facts: 

 if an actinian was placed in a current of water, after expanding, it closed, but 

 it closed much more readily at the time of descending tide; when kept in a current 

 for a long time, the actinians remained closed, but opened irregularly and tem- 

 porarily at the next high tide, and quite generally and persistently at the one after 

 that; mechanical shocks had a tendency to make them open at rising tide and 

 close at falling tide. 



L. Lapicque, in paper number 43, expresses doubt as to the reality of the 

 periodicity thus observed. He raises the point that the rhythm impressed upon 

 the actinians should be that of the tides on the last day of their sojourn under 

 actual tidal influence, and that this would in the course of the next week bring 

 them quite out of accord with the contemporary tidal periodicity. Bohn replies 

 in paper number 9 by showing that the oscillations correspond in a general way 

 to the contemporary tidal rhythm; and in paper number 38, with Fauvel, demon- 

 strates that certain diatoms (Pleurosigma aestuarii) exhibit a tidal rhythm in 

 emergence and disappearance which continues in the aquarium. He admits that 

 mathematical exactness in plotting the curves of such periodicities is impossible 

 (12) (13) (18); Lapicque, unreconciled, suggests that Bohn had better give up 

 the attempt at it, if this be the case (44) (45). 



10. Bohn's study of certain seaside butterflies concerns the relations between 

 phototropism and anemotropism. Satyrus janira orients itself when at rest with 

 head to the wind; its flight is determined by the position of the sun. The more 

 the posterior portion of the eyes is illuminated, the more the wings are spread 

 apart when the insect is at rest, and the more energetically they beat in flight; 

 hence the insect flies away from the sun, especially when it is low. Vanessa 

 cardui shows the same relation between the illumination of the eyes and the beat- 

 ing of the wings, only more strikingly; V. io also shows it, but the relation is the 

 reverse in the case of V. urticae. 



11. This article is a discussion, more or less historical, of the relations between 

 tropisms, instincts, and intelligent acts, in which the conclusion is reached that 

 "Jennings is wholly right in considering supposed tropisms as phenomena in 

 general very complex. But these tropisms depend not only on the connections 

 between organs, but on the state of the matter composing the organs. Living 

 matter has a whole history which is responsibly for the fact that its reactions are 

 made in accordance with determinate rules. Selection, as Jennings conceives 

 it, has but little upon which to exercise itself. The ideas of Jennings, far from 

 invalidating those of Loeb, merely supplement them." 



14, 15, 16, 17. These papers on the reactions of actinians may be considered 

 together. Paper 15 includes the results of the other three. Actinia equina, as 

 we have seen, was found to preserve a tidal rhythm in the laboratory. A day and 

 night rhythm, usually that of opening at night and closing by day, also showed 

 itself. The influence of habitat was indicated by the fact that the day and night 



