20 FOUNDATIONS OF BOTANY 



Examine again and note the blue coloration of the starch grains and 

 the unstained or yellow appearance of other substances in the field. 

 Cut very thin slices from beans, peas, or kernels of corn ; mount in 

 water, stain as above directed, and draw as seen under the microscope. 

 Compare with Figs. 7 and 8. 1 Note the fact that the starch is not 

 packed away in the seeds in bulk, but that it is enclosed in little 

 chambers or cells. 



24. Plant-Cells. Almost all the parts of the higher 

 plants are built up of little separate portions called cells. 

 The cell is the unit of plant-structure, and bears some- 

 thing the same relation to the plant of which it is a part 

 that one cell of a honeycomb does to the whole comb. 

 But this comparison is not a perfect one, for neither the 

 waxen wall of the honeycomb-cell nor the honey within it 

 is alive, while every plant-cell is or has bean alive. And 

 even the largest ordinary honeycomb consists of only a 

 few hundred cells, while a large tree is made up of very 

 many miillons of cells. The student must not conceive 

 of the cell as merely a little chamber or enclosure. The 

 living, more or less liquid, or mucilage-like, or jelly-like 

 substance known as protoplasm, which forms a large portion 

 of the bulk of living and growing cells, is the all-important 

 part of such a cell. Professor Huxley has well called 

 this substance " the physical basis of life." Cells are of 

 all shapes and sizes, from little spheres a ten-thousand th 

 of an inch or less in diameter to slender tubes, such as 

 fibers of cotton, several inches long. To get an idea of 

 the appearance of some rather large cells, scrape a little 

 pulp from a ripe, mealy apple, and examine it first with 



1 The differentiation between the starch grains, the other cell-contents, 

 and the cell-walls will appear better in the drawings if the starch grains are 

 sketched with blue ink. 



