456 BOTANICAL GAZETTE [December 



than by animals, since in the animal the CO2 escapes in the breath as a waste 

 product, while the plant uses the CO2 during day time for the construction of 

 foods." There is regrettable confusion here, involving comparison of incomparable 

 processes. Carbon dioxide happens to be a waste product in animal metabolism, 

 but in addition to this in the case of green plants it is also food material. The 

 contrasting of the work of respiration in the two cases upon this basis is wrong, 

 as the author well knows. As a matter of fact, we have no reason to believe that 

 the work of respiration as done by plant protoplasm is more economical than that 

 done by animal protoplasm. 



That this book successfully meets the demand intended to be supplied by the 

 author is certain, and this is abundant justification for anyone who has the 



run 



-Raymond 



Evolution in the potato beetles 



Although the work of Professor Tcwer^ on Leptinotarsa deals with a 

 group of animals, his book should not be overlooked by botanists on that account. 

 Probably no work since the appearance of DeVries' Mutations iheorie is more 

 worthy of careful study. The contribution is essentially along experimental 

 lines, backed by years of obser\^ation in the field and laboratory. Many of the 

 problems, if not solved, are seen in clearer light, and at least some of the mooted 

 questions may now be dismissed as answered. Every chapter is of interest to all 

 schools of biologists, but there is space here merely for a few of the more important 

 conclusions. The introductory^ chapter on geographical distribution and disper- 

 sion is followed by chapters on variation, coloration, habits, and instincts. Of 

 intense interest are the final chapters, entitled "Production in experiment of races, 

 new characters, and species in Leptinotarsa," and "The" problem of the origin 

 of species." The author believes that only by such careful studies may we ever 

 hope to find out the methods of evolution; we can never solve the problem by 

 inspection. Tower holds that all organic variations are 



responses 



ererm 



plasm .... due to stimuli which produce an inheritable variation differing in 



duced." "Variation i 

 organisms." Another 



permanency 



predetermined 



distinction between fluctuating variations and mutations. Tower secured as good 

 illustrations of mutation in Leptinotarsa as have been obtained in Oenothera, or 



lines 



variations. 

 Jumps, bu 



variations exhibited greater 

 experiments fail to support 



unit characters. In Leptinotarsa also the mutations are orthoge- 



2 Tower, W. L., An investigation of evolution in chrysomelid beetles of the genus 

 Leptinotarsa, Carnegie Institution of Washington, Publ/ no. 48. pp. 320- Wash- 

 ington. 1906. 



