964 



SCIENCE 



LN. S. Vol. XXXIII. No. 860 



trial arts especially rank among the most 

 permanent, not to say eternal, of all the mani- 

 festations of humanity. It is hardly too 

 much to say that only by the extinction of 

 entire peoples are useful arts ever lost (except 

 as superseded by more useful devices) ; and 

 until well within the period of writing any 

 arts possibly lost by extinction of peoples left 

 little trace. 



W J McGee 



SCIENTIFIC BOOKS 

 Light and the Behavior of Organisms. By S. 



O. Mast. New Tork, John Wiley and Sons. 



1911. 



While the present volume deals primarily 

 with the question of the orientation of organ- 

 isms the author tells us that it " may be con- 

 sidered a treatise on the behavior of organisms 

 in their reactions to light." The first three 

 chapters constituting Part I. are devoted to 

 the historical setting of the subject and the 

 statement of general problems and view-points. 

 Part II. is concerned with the way in which 

 organisms turn towards or from a source of 

 stimulation. In addition to giving a very 

 good resume of the observations of others 

 upon orientation this part contains a consid- 

 erable amount of new material from the au- 

 thor's own researches. These include investi- 

 gations of orientation in Indian corn, Nas- 

 turtium, Amoeba, Euglena and a few other 

 flagellates, the swarm spores of CEdogonium, 

 Hydra, Eudendrium and some worms and in- 

 sect larvEe. In general this work gives evi- 

 dence of having been done with care and ac- 

 curacy and adds materially to our knowledge 

 of the general modus operandi of orientation. 

 It is evident now to every one who has fol- 

 lowed the work in this subject during the past 

 few years that orientation is accomplished by 

 a great variety of methods in different organ- 

 isms. There is no such thing as a general 

 scheme of orientation. 



Loeb's theory of orientation is the author's 

 favorite object of attack and he recurs to this 

 doctrine and certain other views of Loeb with 

 the persistence of Cato in urging the destruc- 

 tion of Carthage. It is not difficult to adduce 



cases that do not fall under Loeb's explana- 

 tion of the way in which animals become 

 oriented, but some of Mast's own investiga- 

 tions seem to afford about as good support as 

 has been furnished for the theory which he so 

 persistently attacks. No clearer case of 

 orientation through the local response of the 

 part directly stimulated could well be imag- 

 ined than the one afforded by Amoeba, and the 

 author admits that the " method of orienta- 

 tion is in harmony with much in Verworn's 

 theory and also with the essentials in Loeb's." 

 But he adds that " it does not, however, sup- 

 port the idea connected wdth these theories, 

 that a constant intensity produces a constant 

 directive stimulation." I am not sure that I 

 understand the pertinency of the criticism, 

 for there is nothing in the theories of either 

 of these writers which implies that the actual 

 stimulating effect of any directive agency is 

 subject to no variation. Both of these writers 

 have adduced several cases which show that 

 such variation occurs, and it is out of the 

 question to suppose that either of them has 

 overlooked the obvious importance of internal 

 changes in determining the way in which an 

 animal responds. 



The author's experiments on the larvae of 

 Arenicola are of especial interest in regard to 

 the problem of orientation. There is no ref- 

 erence either in the text or in the bibliography 

 to the previous work of Lillie on the method of 

 orientation in this form, although there is a 

 quotation from a paper by Lillie dealing with 

 certain features of its structure and develop- 

 ment. The observations of Lillie are in gen- 

 eral confirmed, but Mast has performed sev- 

 eral additional experiments which bring out 

 more clearly the fact that orientation is " due 

 to difference of intensity on opposite sides " of 

 the organism. The orienting response is 

 shown to be due to light falling upon the eyes, 

 the other parts of the body being apparently 

 insensitive to this stimulus. When the larva 

 is suddenly illuminated on one side there are 

 no random or trial movements, but the head is 

 bent directly toward the source of light. 

 All the evidence points to the conclusion that 

 orientation is the result of comparatively 



