PREFACE 



WHILST giving a course of lectures on Heredity to a class 

 of working men and others, I was asked to recommend a 

 textbook which could be read up by the students in order 

 that they might be able to make the best possible use 

 of what they heard during the lectures. I felt extremely 

 sorry that I was unable to comply with that request. I 

 could not find a single book in the English language suitable 

 for that purpose, seeing that, apart from a little superficially 

 written book of no consequence, only the large special text- 

 books on the subject are available. 



As there must be a good many such intelligent and 

 aspiring young people eager for a deeper knowledge of the 

 problem of life, without being at the same time advanced 

 enough to master the larger manuals, I at last decided to 

 follow the advice of my friends and write the book myself. 



It will therefore be seen that I claim no originality for 

 the contents of this book. Its purpose is to supply in a 

 simple and yet scientific manner all that may be desirable 

 for the average intelligence to know about Heredity and 

 related questions, without at the same time assuming any 

 previous knowledge of the subject on the reader's part. 



S. H. 



MANCHESTER, 

 January, 1910. 



