52 TENOPYR: CONSTANCY OF CELL SHAPE 
ponding variations in cell size, or whether the cell size of each 
‘species is a constant and distinct character. That is, do environ- 
mental conditions, which modify the size of plant organs, affect 
the size of their cells? Are giants and dwarfs due to greater or 
lesser development in size of the individual cells, or to more or less 
numerous cell divisions? 
Amelung estimated the size of the various cells of plants having 
homologous organs differing in size. He made ten longitudinal 
sections, or, in other plants, ten cross sections of each of the organs 
to be compared. These he mounted in water or in glycerine. In 
each section he counted the number of cells of a given tissue that 
were intersected by a line on the stage micrometer, a line usually 
I mm., sometimes 5 mm., in length. He thus obtained ten cell 
counts on each organ. From these he determined the average 
number of cells to 1 mm. and the average length or average 
breadth of the cells of a given tissue both of the giant and of the 
dwarf organs. He compared the palisade and epidermal cells of 
large leaves with similar tissue cells of small leaves, the wood cells 
of poorly developed and of well-developed shoots, and the paren- 
chyma of large and small fruits. The organs compared were 
taken from the same plant, or from different plants of the same 
species, or from closely related species. He found that the cell 
size of a given tissue of an organ is constant for the species, re- 
gardless of the average size of the individual or of the organ. 
Thus, the epidermal cells of a small leaf of Ficus macrocar pus 
were as large as those of a leaf twice as long and broad; the 
wood cells of a twig of Vitis vinifera, 6 mm. in thickness, measured 
as much in cross section as those of another shoot, only half as 
thick; a leaf of Victoria regia, measuring 900 X goo mm., and 
one of Nymphea alba, 190 X 190 mm., had cells that were identical 
in size. 
Amelung concludes that not the cell size, but the cell number, 
determines the size of an organ. 
Sachs, with whom Amelung worked, confirms the statement 
that the cell size of a given species is constant, and is not influenced 
by body size. 
Strasburger (1893), in a series of studies on the relation of 
we nuclear and cell size in the embryonic cells of the growing points 
