8 Plant Tissue Culture 



cies and could not be altered by contact with or 

 even dependence on the tissues of another species 

 (Vochting, 1894, 331). The transplantation ex- 

 periments demonstrated the restrictions which 

 species places on the potencies of a cell. The dis- 

 section experiments demonstrated the essential 

 totipotency of the cell within these species limita- 

 tions. Similar conclusions may be drawn from 

 experiments with animal materials (Figs. 3, 4). 



To carry this method of dissection to its logical 

 end, we would have to go to the cells themselves, 

 as we have already said. Implicit in Schleiden 

 and Schwann's concept, subjected to a preliminary 

 pragmatic test by Vochting, this idea seems never- 

 theless not to have been explicitly formulated as 

 a basis for planning experiments with either plant 

 or animal materials until much later. In the early 

 years of the present century, Haberlandt (1902, 

 98) (Fig. 5) set forth the principle frankly and 

 lucidly in the words that I have placed at the head 

 of Chapter II. He then proceeded methodically 

 to fill the gap in our knowledge, the existence of 

 which he had called to our attention. He set out 

 to grow cells and small groups of cells in suitable 

 nutrients and to study their behavior. The dis- 

 cipline which Haberlandt thus outlined is that 

 which, in the four decades since his paper, has 

 gradually crystallized into what we know today 



