Mat 11, 1906.] 



SCIENCE. 



743 



diverse problems in which our author has done 

 pioneer work. The following incident might 

 give us perhaps the key to his starting point. 

 From 1886 to 1888 Loeb was assistant in (ani- 

 mal) physiology in Wiirzburg. At that time 

 the chair of botany at that university was 

 occupied by Julius von Sachs, one of the fore- 

 most plant physiologists, who made a special 

 study of tropism in plants and whose cele- 

 brated lectures on plant physiology appeared 

 in 1887 in a second edition. This great in- 

 vestigator apparently exerted a lasting in- 

 fluence upon the direction of Loeb's searching 

 mind. Thus we find that the first larger piece 

 of work of our author consists in a pamphlet 

 entitled : ' The Heliotropism of Animals and 

 its Identity with the Heliotropism of Plants.' 

 That pamphlet forms the first paper of this 

 collection. Through a number of ingenious 

 but simple experiments it is shown for the 

 first time how the dependence of animal move- 

 ments on light is in every point the same as 

 the dependence of plant movements on the 

 same source of stimulation. In the next paper 

 it is shown that the same holds good also for 

 the movements of sessile animals. In other 

 papers which followed, the influence of gravity 

 upon the movements of animals (geotropism) 

 and the influence of contact irritability 

 (stereotropism) were studied and were also 

 found to be identical with the same influences 

 in plants. The similarity of these phenomena 

 in animals and plants demonstrated to Loeb 

 their independence of a nervous mechanism, 

 and in a paper on ' Instinct and "Will ' he 

 comes to the conclusion that what has been 

 I taken for the effect of ' will ' or ' instinct ' is 

 really the effect of light, gravity, friction, 

 chemical forces, etc. In a study upon 

 ' Heteromorphosis ' he shows that by the above- 

 mentioned physical influences, as in plants, 

 the regeneration in some animals would lead 

 to the production of an organ different in 

 form and function from the original one. In 

 this study the factor of turgescence, of hydro- 

 static pressure is mentioned for the first time. 

 In a further study on ' Organization and 

 Growth ' upon marine animals it was found 

 that besides the above mentioned physical 



factors, the concentration of the sea water 

 was an important factor, there was no growth 

 nor regeneration in concentrations above 5.4 

 per cent, nor below 1.3 per cent. ' Further- 

 more, the presence of oxygen as well as of 

 potassium and magnesimn was indispensable. 

 From now on we meet with studies in which 

 the importance of oxygen and especially of 

 osmosis as physiological factors were consid- 

 ered in the first place. We meet them in the 

 ' Experiments on Cleavage,' in the studies ' On 

 a Simple Method of Producing from one Egg 

 two or more Embryos which are Grown To- 

 gether,' in the studies on the ' Sensibility of 

 Fish Embryos to Lack of Oxygen and Loss of 

 Water,' etc. Meanwhile the studies of Van't 

 Hoff, of Arrhenius and of Ostwald upon os- 

 motic pressure and dissociation of electrolytes 

 created a new epoch in the sciences of physics 

 and chemistry, and we find Loeb henceforth 

 profoundly engaged in unraveling the mys- 

 teries of life with the aid of the newly estab- 

 lished science of physical chemistry. The 

 fruit of these new efforts we find laid down 

 here in numerous papers on ' Artificial Par- 

 thenogenesis,' on the physiological effects of 

 ions, on ion-proteids, on the effect of ions on 

 contractility, on the toxic and antitoxic effects 

 of ions, etc. It is, of course, impossible to 

 give here any intelligible account of the mul- 

 titude of important new facts laid down in 

 these papers. We have here before us the 

 fruit of a most indefatigable and ingenious 

 investigator who has done pioneer work in 

 many fields in biology. These studies will be 

 a source of instruction and stimulation to 

 many an earnest student in general physiol- 

 ogy, and we ought to be thankful to the author 

 as well as to the editors of the Decennial 

 Publications of the University of Chicago for 

 presenting to us the collection of these very 

 valuable studies. 



S. J. Meltzer. 

 Rockefeller Institute. 



SCIENTIFIC JOURNALS AND ARTICLES. 



The American Naturalist for April con- 

 tains but three papers : the first ' The Fresh- 

 water Copepoda of Massachusetts,' by A. S. 

 Pearse, adds seventeen species, two new, to 



