

4x6 



THE QUARTERLY REVIEW OF BIOLOGY 



stellation of genes peculiar to the germ- 

 plasm of each species but it will be long 

 before we have a causal explanation of the 

 gene pattern of each particular germ-plasm. 

 In surveying the status of experimental 

 embryology today one cannot fail to be 

 impressed with the fact that as yet but few 

 causal explanations of developmental 

 processes have been established. Only a 

 small percentage of the experiments de- 

 scribed are really causal-analytical in 

 Roux's sense; the bulk of them would have 

 to be described as descriptive experiments 

 and not a few would fall into his category 

 of blind experiment. However, the main 

 service of many experiments, as Professor 

 Morgan has pointed out, has been to re- 

 veal new possibilities and the outlook for 

 further advance has never been brighter 



then at present. One of the great services 

 which Professor Morgan has rendered us 

 in writing his book has been to point out 

 clearly the limitations of many experi- 

 mental procedures and to suggest other 

 attacks and new problems for solution. 

 The book will prove therefore, a stimulus 

 to many future types of work. We look 

 forward eagerly to the second volume. 



Fortunately, perhaps, von Baer's state- 

 ment is as applicable today as it was in 



Noch manchem wird ein Preis zu Theil werden. 

 Die Palme aber wird der Gliickliche erringen, dem es 

 vorbehalten ist, die bildenden Krafte des thierischen 

 Korpers auf die allgemeine Krafte oder Lebensricht- 

 ungen des Weltganzen zuriickzufiihren. Der Baum 

 aus welchem seine Wicge gezimmert werden soil, 

 hat noch nicht gekeimt. 



