﻿CURRENT LITERATURE. 



BOOK REVIEWS. 

 Influence of light and darkness. 



The relation of light to the growth and development of plants has 

 been the subject of much study and experimental research for two centuries 

 or more. Probably the largest contribution to the general knowledge of the 

 subject, at least to the text-book literature, has been made by Sachs, aided by 



his pupils. He began publication in 1859, and exerted great influence in 

 molding scientific opinion in this as in other parts of the science of plan 

 physiology. As researches have multiplied and the subject has unfolded, the 

 difficulty of making a satisfactory explanation of observed phenomena has 

 increased. 



A careful examination of the whole subject, coupled with observations 

 upon a series of plants of wide relationship and diverse habits, has been much 

 needed. A inonographic work of this character has recently been published 

 by Dr. D. T. MacDougal/ director of the laboratories of the New York 

 Botanical Garden. It has been the aim of the author to secure ample facts 

 with which to survey the whole field, and the* substantial volume before us is 

 evidence of success. 



The work opens with a resume of previous contributions, in which mere 

 than a hundred works are summarized in a lucid and critical manner. The 

 author then records his own observations, giving an account of experiments 

 on ninety-seven species of flowering plants, ferns and their allies, which have 

 been grown in continual darkness, with control plants grown in light. The 

 subjects were grown from tubers, corms, rhizomes, cuttings of leaves and 

 stems, seeds, and spores. They represent aquatics, creepers, climbers, suc- 

 culents, mycorhizal forms, geophilous and aerial shoots, mesophytes, and spmy 

 xerophytes. The work has extended over a period of seven years, and 

 embraces a wealth of data not readily apprehended without detailed examina- 

 tion. The great number of excellent original illustrations adds interest and 

 value to the treatise. 



A third of the volume is occupied with a discussion of the data, and their 

 correlation with previous observations and conclusions. The matter is taken 

 up from various points of view, and it is clearly shown that no theories here- 

 tofore propounded will apply to all cases. Although occasionally plants have 

 acquired certain advantages through etiolation, the forms assumed in dark- 



^ MacDougal, Daniel Trembly, The influence of light and darkness upon 

 growth and development. Memoirs of the New York Botanical Garden, II. Inip. 

 8vo. pp. 319,^^^. ijb. New York Botanical Garden. 1903. ^2.00. 



292 y^^^^^ 



