INTRODUCTION. 



"The Lord gave and the Lord hath taken away." In such words 

 man has been wont to blame Providence for the consequences of his 

 own errors and ignorance. Happily this ignorance is being grad- 

 ually brushed away and man is learning little by little that there 

 are some ills for which he himself is responsible. If there is one 

 thing more than another which we have been in the habit of charg- 

 ing up against Providence it is the results of vicious or defective 

 heredity, yet instead of being a mysterious dispensation of Provi- 

 dence, heredity is the product of natural laws operating along certain 

 prescribed lines. Instead of having a science of heredity our 

 knowledge of the subject has consisted of a series of disconnected 

 facts wholly inadequate to give us an intelligent idea of the processes 

 of Nature. We have known that the children of white parents 

 are white and that the children of colored parents are colored, but 

 we have known little else. Laying the blame for disastrous results 

 upon the shoulders of Providence is but one way of confessing 



this ignorance. 



KINDS OF HEREDITY. 



Heredity is of two kinds; first. Structural Heredity, which re- 

 lates to the size, form and color of an organ without regard to the 

 force or energy that may reside in it; and second. Dynamical Her- 

 edity, which relates to the force, power or energy of an organ 

 without regard to its size or form. 



Heretofore attention has been principally directed to structural 

 heredity, and examples of the known facts and the theories relating 



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