9 



REVIEWS 



Juvenile Forms and Flower M aturity * 



During a residence in West Australia, Diels found the relation 

 between vegetative growth and generative maturity subject to 

 change and became acquainted with the conditions that corre- 

 spond to the phases of these changes. He found a large number 

 of cases in which flowering occurred in juvenile forms. A search 

 in the literature showed that this "abnormality" is far-reaching 

 and calculated "to throw light upon a new side of form-diversity 

 in the plant kingdom." 



His book does not attempt a complete enumeration of such 

 cases but endeavors, by typical examples, to illustrate the many- 

 sidedness of the question. 



The first chapter, entitled, " Die Bedingtheit dcr Blutenrcife" 

 discusses various explanations that have been offered as to the 

 conditions of flowering. The older theory of Moebius (1847) 

 was that every plant species which, through heredity, possesses 

 fixed characters, produces flowers at a definite age or phase of 

 its development. Diels, however, agrees with the view more 

 recently expressed by Klebs (1904), " that flower formation by 

 phanerogamous plants presents the same problem in principle as 

 does the sexual reproduction of algae, or the fruiting of the 

 higher fungi. * * * "I hold," says Klebs, "that a quantita- 

 tive increase of the concentration of organic material with all its 

 physical and chemical consequences plays an important role in 

 the transition from growth to reproduction." " The external cir- 

 cumstances," says Diels, "either inhibit or accelerate, according 

 as they interfere with or favor, the internal conditions necessary 

 to flowering." Experimental researches on the problem have 

 been few, but Diels believes that a new review of the cases 

 hitherto published of flowering in a very early developmental 

 stage will not be without its value. 



Chapter H, " Das Verhdltniss der Blutenreife sur vegetativen 

 Entivickehing in seiner Wandelbarkeit,"" gives citations from litera- 

 ture, presenting cases illustrating the relation of flowering to 



* Diels, L. Jugendformen und Blutenreife im Pflanzenreich. Pp. 1-130. f. 

 1-30. Berlin : Gebriider Borntraeger. 1906. 



