May 8, 1903.] 



SCIENCE. 



737 



tention of the calcium sulpliate method for 

 testing for barium and strontium, which has 

 been abandoned by Fresenius and others, is 

 open to criticism, and the failure to mention 

 de Koninck's excellent potassium cobaltic ni- 

 trite test for potassiimi seems unfortunate in 

 view of the increasing cost of platinum, and 

 of the fact that the test is much more deli- 

 cate than the one with hydrochloroplatinic 

 acid. Those who have used Gooch's separa- 

 tions of lithium chloride from sodium and 

 potassium chlorides, and of calcium nitrate 

 from strontium nitrate, by means of amyl 

 alcohol, will regret that they receive no men- 

 tion here. 



A striking and valuable feature of the book 

 is the elaborate treatment of the equations 

 of the reactions. In these equations the 

 formidas are frequently rather elaborately 

 developed according to the theory of valency, 

 a practice which at times seems to involve an 

 unnecessary waste of space, on account of the 

 uncertainty of the positions of the atoms in 

 the inorganic compounds. 



The part on the acids is unusually full and 

 extensive, including a number of acids that 

 are not usually considered in the text-books. 

 There is a supplement, also, which deals with 

 the rarer metals. 



Analytical tables, to which some teachers 

 object, are freely used, but it is stated that 

 in the author's experience these have given 

 the best results. 



The translation appears to have been very 

 well done, but a number of errors, particularly 

 in the equations, indicate some lack of care 

 in proof-reading. H. L. W. 



The Movements and Reactions of Fresh-water 

 Planarians : A Study in Animal Behaviour. 

 By Eaymond Pearl, Ph.D. The Quarterly 

 Journal of Microscopical Science. Vol. 46, 

 1903, pp. 509-714. 



This paper from the zoological laboratory 

 of the University of Michigan gives a de- 

 tailed account of a very thorough and care- 

 ful study of the behavior of planarians. Dr. 

 Pearl states in his introduction that it is his 



purpose to give such a complete account of , 

 his observations that no desired information 

 concerning the work shall be lacking. In 

 America, especially among physiologists, the 

 tendency is to limit papers to the bare state- 

 ment of results; details of method and ob- 

 servation are omitted. This Dr. Pearl con- 

 siders an unfortunate tendency; he, therefore, 

 presents a minutely descriptive paper. But 

 even two hundred pages on planarian be- 

 havior are not tiresome in this case, for the 

 paper is written with a noteworthy clearness, 

 accuracy and precision of statement. Every- 

 where it inspires confidence in the reliability 

 of the observations and experiments. The 

 author's painstaking care, resourcefulness and 

 enthusiasm for research are unmistakable. 

 Although Dr. Pearl is evidently responsible 

 for the whole of this study, he gives generous 

 thanks to Professor Herbert S. Jennings for 

 suggestions, criticisms and general helpful- 

 ness. Professor Jennings is really the pio- 

 neer in the analytic study of animal behavior 

 in this country, and his excellent work on the 

 reactions of unicellular organisms is inspiring 

 many to research along similar lines. 



In the paper at hand we find the following 

 chapters: (1) 'A Eesume of the Literature 

 Bearing on the Subject,' (2) 'A Discussion 

 of the Habits and Natural History of Pla- 

 narians,' (3) ' A Description of the Normal 

 Activities of the Animals,' and (4) 'A Con- 

 sideration of Their Eeactions to Stimuli.' 

 In this chapter the author deals with: (a) 

 reactions to mechanical stimuli, (b) reactions 

 to food and other chemical stimuli, (c) thig- 

 motactic and righting reactions, {d) reactions 

 to an electric current, (e) reactions to desic- 

 cation, and (f) reactions to currents of water 

 (rheotaxis). 



Throughout the investigation Dr. Pearl's 

 aim has been to analyze all the reactions into 

 their reflex components and to describe the 

 mechanism of each reaction. Briefly stated, 

 the most important results of the investiga- 

 tion are as follows : (1) The normal locomotor 

 movements of planarians are two : gliding, by 

 the beating of the cilia on the ventral surface, 

 and craivling, due to longitudinal waves of 

 muscular contraction. (2) The animals fa- 



