JULIUS SACHS. 169 



essays upon the connection between cell-formation and 

 growth, which in my opinion belong to his most brilliant 

 achievements. As a result of Nageli's researches on the 

 apical cell, numerous botanical works had arisen dealing 

 with the laws of cell-division. It was this tendency, 

 exaggerated until it was justly dubbed " zellfangerei," that 

 led men to neglect plants and organs as a whole for the 

 mere cells, and to take it as granted that growth is de- 

 termined by the manner and method of cell-division, 

 much as the shape of a building is determined by the 

 way the building-stones are laid one upon another. 



Hofmeister's brilliant, though hardly well-grounded, 

 opposition had but little success : only a few botanists 

 took any notice of it. It was Sachs who, in his usual 

 clear manner and by the aid of simple contrivances, first 

 explained the relations between cell-disposition and growth. 

 In his opinion, the latter is the determining factor, the 

 arrangement of cells depending upon growth. This ex- 

 plained why, for instance, cross-sections through cylindrical 

 masses of cells in plants belonging to widely separated 

 groups may present the same appearance of cell-arrange- 

 ments, as a developing alga or a hair of a dicotyledon. 

 The introduction of the terms " anticlinal " and " periclinal " 

 made a brief, striking bird's-eye view of the matter possible, 

 and facilitated further study of the changes in cell-disposi- 

 tion occurring during growth. A large group of facts was 

 brought together under a common heading ; and not only 

 was the way made smooth for further investigations into 

 the causes of the arrangement of cells, but an important 

 point of departure was also made for experiments on the 

 evolution of organs which do not possess an apical cell. 



The changes, which had gradually taken place in the 

 cell theory, have led to an entire alteration in its original 

 meaning. This prompted Sachs, who always felt the need 

 of clear and consequently historically correct conceptions, 

 to introduce the definition " Energid" . In my opinion he 

 thereby rendered good service to science. It was a great 

 satisfaction to him that his achievements found favour with 

 the most eminent histologists (Kupffer for instance), and 



