and Laboratory Methods. 1669 



femur itself instead of in the trochanter, as is usually the case in insects where 

 autotomy does not occur. The actual separation of the appendage takes place 

 in one of two ways, depending primarily on the strength of the stimulus causing 

 it. Strong stimuli cause a sudden breaking of the limb at the preformed place, 

 provided it is in a fixed position so as to make this mechanically possible, 

 while weaker stimuli more often cause a slower separation resulting from histolytic 

 processes. In both cases the wound is immediately closed and bleeding 

 prevented by the cells of the diaphragm becoming tightly packed together. 

 That the autotomy is a purely reflex phenomenon is proven by the fact that it 

 can be induced in a decapitated animal exactly as well as in a normal. A very 

 full bibliography of the subject is appended. r. p. 



Jennings, H. S., and Crosby, J. H. Studies on The authors find that certain bacteria 



Reactions to Stimuli in Unicellular Organ- j-gspond tO Stimuli by a reaction of a 

 isms. VII. The Manner in which Bacteria ^ •' 



react to Stimuli, especially to Chemical reflex type, comparable to the " motor 



Stimuli. Amer. Jour. Physiol. 6:31-37, reflex " of the flagellate and ciliate in- 



I90I. ° 



fusoria previously described by Jen- 

 nings. The " motor reflex " of the bacteria studied was found to be merely 

 movement in the opposite direction to that taking place before stimulation. 

 For example, a specimen of Spirillum when stimulated swims straight backward 

 away from the stimulus, and then after a time swims straight ahead again. 

 This was found to be the method of reaction to chemicals ; no orientation is to 

 be observed and collections are formed in solutions of optimum concentration 

 as a result of this " motor reflex " in essentially the same way as are the collec- 

 tions of infusoria. r. p. 



Brasch, R. Die Anwendung der physikali- ^or some time a need has been felt 



schenChemieauf die Physiologic undPatho- for a work which would digest and 

 logie. Wiesbaden (J. F. Bergman). Pp.202, ^ . ^ ^ 1 ^ , r 



jQQj to / r . present m a not too abstract form 



those results of physical chemistry 

 which may be brought into relation with, and used in biological work. The 

 nearest approach which has been made towards fulfilment of this need is to be 

 found in the present work. The principal objection which can be made to the 

 book is that it develops the subject from the standpoint of pure human physi- 

 ology, yet its treatment is on the whole so broad that this is not at all a serious 

 drawback. 



The work is divided into three main parts as follows : I. " The Physical 

 Chemistry of the Salts in the Human Organism," containing a clear and simpli- 

 fied discussion of the laws of solutions, ionic dissociation and chemical change 

 as based on the modern physico-chemical theory. In this section is also taken 

 up the subject of the chemical composition of the organic salts of the organism 

 and their relation to the cells and tissues. Part II deals with "The Oxidation 

 Process in the Human Organism," while Part III is devoted to " The Energy 

 Relations of the Human Organism." Here the author takes up the general 

 question of how the organism gets its available energy during metabolism and 

 develops a quantitative chemical theory for the process. 



In concluding the author points out the possibilities for research in physi- 



