Chap, i The Cell 



193 



the new cell walls were first investigated by Hofmeister in 

 1867, but received a fuller explanation from Sachs in 1878. 

 He showed that the new wall is always produced at right 

 angles to the side walls of the dividing cell and distinguished 

 between the periclinal and the anticlinal membranes, the 

 former term being applied to those which arise so as to 

 be parallel with the external surface of the mass of tissue 

 or growing-point, and the latter to those at right angles 

 to the former. The sequence of formation was worked out 

 more completely in 1886 by Errera and by Berthold. 

 They showed that in the majority of cases the process of 

 construction is such that the new walls exhibit the 

 minimum of surface possible. 



GREEN 



