HEREDITY AND VARIATION 217 



have at present no real idea of how the here- 

 ditary characteristics are transmitted. There 

 have been various attempts to solve this riddle 

 to which some attention must now be paid. 

 In the first place there is what is known as the 

 Particulate group of theories to which the Dar- Participate 

 v/inian Pangenesis belongs. According to this the es 

 and other similar theories small germs Dar- 

 win's pangenes, also called by other names by 

 other theorists such as Galton, but all meaning 

 the same thing are shed from each part of the 

 body, collected in the ovum or spermatozoon 

 and grow in the developing individual, produ- 

 cing, so to speak, the plants from which they 

 were shed. 



It is the most obvious theory and in one way 

 or another it may be said that it is the theory 

 which commands the greatest amount of sup- 

 port to-day. There are two points, however, 

 1o be considered in connection with it. In the 

 iirst place the theory requires it to be assumed 

 1hat amongst the germs contained in the sex- 

 product there shall be not only representatives 

 of even the smallest parts of the parental bodies 

 -since the very smallest peculiarities may be 

 transmitted and even for generations but also 

 of all the ancestors of those parents since 

 atavism or " throws-back" have to be taken into 

 consideration . Hence it has been urged by some 



