BODY SIZE AND CELL SIZE 161 



in their number, or to both, is one of fundamental interest and 

 importance. 



Some of the earliest observations in this field were made by 

 botanists and served to show that differences in body size are due 

 to the number of cells present rather than to the size of the indi- 

 vidual cells. Erich Amelung ('93) determined ''that the larger or 

 smaller development of a plant body has no influence on the size 

 of its adult constituent cells." Sachs ('93) also called attention 

 to the lack of correlation between cell size and body size. Stras- 

 burger ('93) reached the same conclusion concerning the embry- 

 onic cells from the growing points of extremely large and small 

 individuals. He says: » 



Not the cell size, onty the cell number, is influenced by the different 

 size of an individual . . . . It was surprising to me to find that while 

 individuals of the same species always showed the same size of embry- 

 onic nuclei and cells, varieties of these same species might differ greatly 

 from each other. 



In an interesting paper on one of the mutants of Oenothera 

 lamarckiana, O. gigas, Gates ('09) comes to practically the same 

 conclusion. He says (p. 543) : 



In 0. gigas we have an organism built of bricks which are larger and 

 whose relative dimensions are also altered in some cases. These two 

 factors will apparently account for all the differences between 0. gigas 

 and O. lamarckiana, and the second factor may be one merely of readjust- 

 ment consequent upon the first. It is probable that the number of 

 cells is approximately the same in both cases. 



This is evidently one of those cases, of which Strasburger speaks, 

 in which different species or varieties of the same species may differ 

 greatly from each other in cell size. 



In the case of animals the earlier work on cell size was confined 

 largely to studies on nerve cells and fibers. Gaule ('89) concluded 

 from a study of the spinal cord of the frog that differences in the 

 size of individuals of the same species influenced only the size of 

 the ganglion cells but in no way influenced their number, which 

 might be considered a constant factor. Donaldson ('95) after 

 summarizing a number of observations on the number and size 

 of nerve cells in man says (p. 192) : 



