PERIODICAL LITERATURE 

 BOTANY AND ZOOLOGY 



Paraphrasing parts of a volume published in 

 Origin 1914. ^^c Monde Vegetal, by Gaston Bonnier, the 



of reviewer makes special account of the theories of 



Species the origin of species. While there is nothing new 



in these theories, they are clearly stated and 

 argued. There are three theories — the Darwinian theory of evolution, 

 working slowly through centuries or millenniums, which appears largely 

 abandoned ; the Lamarkian theory of adaptation under the influence of 

 environment; Xaegeli's theory of mutation, the changes being due to 

 disposition in the egg cell. This last theory has been proved as long 

 ago as 1761 by Duchesne, who saw a single-leaf strawberry appear 

 without transition stages from the three-leaved one, which has per- 

 sisted and propagated its kind. De Vries, Nillson. and Blaringhem 

 have furnished numberless cases of the creation of new species by muta- 

 tion. But there is in addition open the possibility of the environment 

 producing modifications which become hereditary. 1 'roofs of this are 

 cited at greater length. 



Modifications due to a watery environment have been secured in 

 brambles (?ronce!) and in the yellow-flowered water lily (Nuphar) 

 and in other plants, as regards anatomic structure and in character of 

 foliage, ampl)- proving that air plants and semi-air plants are capable of 

 profound modifications to adapt them to live in a watery environment. 

 Just so, plants from a humid region transplanted to a dry climate, and 

 vice versa, change the structiu'e of their foliage, spines, etc. Soil-mois- 

 ture differences have a well-known influence on plant development. 

 ( )ther modifications result from the chemical character of the soil. Re- 

 duction of salt in the soil turns Matricaria )iiaritima into Matricaria 

 inodora; presence of salt leads to thickening of the leaves due to in- 

 crease in chlorophyll cells. ".V leaf of oats resembles one of wheal 

 more clcsely if grown with the same mineral constituents in the soil 

 than two blades of wheat grown with ditTeri-nt soil constituents." Cal- 

 cifuge and calcicdlc plants arc ofti'n nioditled from one to the <itlH'r 

 situations. 



Finally, light i> a powiTtul iiiodituT ol pl.iiil sinuture and dcvclop- 

 mrnt. Withdrawal of light may change .'in .nnuia] into a pennni.'d 



