Physiologie. 91 



logical States as determining factors in response to Stimuli, finds 

 reactions very different according to the physiological state of 

 the organism. Sets iourth view that tiie Stimulus changes the 

 State oi the organism as a whole and that the change induces 

 a certain type of reaction. 



The longest and most elaborate paper of the series is the 

 sixth, on the movements and reactions of Amoeba. Among 

 other things, concludes that the extension of pseudopodia cannot 

 be accounted for by local decrease in surface tension and simi- 

 larly maintains that the effects of Stimuli in governing the 

 movements of Amoeba cannot be due to this cause. „All the 

 results taken together lead to the conclusion that neither the 

 usual movements nor reactions of Amoeba have been as yet 

 resolved into known physical factors. There is the same un- 

 bridged gap between the physical effect of the Stimulus and the 

 reaction of the organism that we find in higher animals. In 

 the behavior of Amoeba we may distinguish factors comparable 

 to habits, reflexes, and automatic activities of higher organisms. 

 Its reactions as a rule are adaptive.'' 



The concluding paper of the series is in effect a summary 

 and general consideration of what has gone before, it is calied 

 „The Method of Trial and Error in the behavior of Lower 

 Organisms". Considers reactions as a result of this method 

 and that this is in complete contrast to the tropism idea. The 

 best notion of the point of view may perhaps be given by the 

 quotations from the author's closing paragraph. „This work 

 has shown that in these creatures the behavior is not as a rule 

 on the tropism plan — a set, forced method of reacting to 

 each particular agent — but takes place in a much more flex- 

 ible^ less directly machine like way, by the method of trial and 

 error. Tropic action doubtiess occurs, but the main basis of 

 behavior is in these organisms, the method of trial and error." 



H. M. Richards (New York.) 



Russell, W. J., On the action of wood on a Photo- 

 graphic Plate in the Dark. (Proc. Royal Soc. London. 

 Sept. 28, 1904.) 



All woods are capable of acting on a Photographie plate 

 in the dark and producing a picture of themselves. The 

 wood of Conifers is very active. In Pinus sylvestris the rings 

 formed during the first stages of a year's growth produce in 

 the picture dark rings, the later formed wood giving lighter 

 rings in the Image. Oak, beech and Robinia give good pic- 

 tures; ash, elm, horse-chestnut and plane have but little acti- 

 vity. Many resins are very active while true gums are in- 

 active. Occasionally the picture on the plate does not resemble 

 the markings visible in the wood. No explanation of this fact 

 has been given. Bark and pith are inactive. If previously 

 exposed to strong light the wood is much more active. It is 



