FOREWORD 



I AM delighted, but not surprised, that a new edition of 

 "Recent Advances in Cytology" has been called for, and am 

 fortunate in being permitted to write a foreword for it. The book 

 is concerned with those aspects of cytology which have a bearing 

 on genetics, and therefore deals mainly with the nucleus. But a 

 study of the mechanics of nuclear division inevitably involves that 

 of extra-nuclear structures such as the centrosome ; and a great 

 deal of light is thrown on the nature of protoplasm by its peculiar 

 behaviour when organised on the spindle. 



Modern cytology has two very remarkable features. Its principles 

 are the same for plant and animal cells. From a study of the 

 chromosomes in the Liliaceae we can clear up previously obscure 

 phenomena in the nuclei of the Orthoptera, and conversely. And 

 the remarkably uniform behaviour of nuclei makes deduction and 

 prediction possible on a very much larger scale than in any other 

 field of morphology and physiology. Thus the principles deduced 

 largely from a study of the monocotyledons led to the prediction 

 of phenomena which were verified in the genetics of man. 



Further, the uniformity of the nuclear mechanisms can be 

 extrapolated with great confidence into the past. We can be 

 reasonably sure that an Acanthodian or a Pteridosperm nucleus was 

 organised on modern lines. We can therefore deduce that the 

 principles of genetics and the method of evolution were much the 

 same in remote geological epochs as they are to-day. Just because 

 the nuclear mechanism has apparently reached the limits of its own 

 evolution it furnishes a basis for the evolution of other characters. 

 An attempt to study the evolution of living organisms without 

 reference to cytology would be as futile as an account of stellar 

 evolution which ignored spectroscopy. 



The first edition of this book was the object of numerous attacks. 

 In fact, one of the sessions of the Sixth International Congress of 



