DIFFERENCES BETWEEN ANIMALS AND PLANTS 



II 



sists of a series of changes in the arrangement of the intranuclear network, 

 resulting in the exact division of the chromatic fibers into two parts, which 

 form the chromoplasm of the daughter nuclei. The changes follow a closely 

 similar course in both plant and animal cells. 



Differences between Animals and Plants. Having considered at 

 some length the vital properties of protoplasm, as shown in cells of animal 

 as well as of vegetable organisms, we are now in a position to discuss the ques- 

 tion of the differences between plants and animals. It might at the outset 

 of our inquiry have seemed an unnecessary thing to recount the distinctions 

 which exist between an animal and a vegetable as they are in many cases so 

 obvious, but, however great the differences may be between the higher ani- 

 mals and plants, in the lowest of them the distinctions are much less plain. 



FIG. ii. Karyokinesis, Mitosis, or Indirect Cell Division (diagrammatic). A, Cell 

 with resting nucleus; B, wreath, daughter centrosomes and early stage of achromatic 

 spindle; C, chromosomes; D, monaster stage, achromatic spindle in long axis of nucleus, 

 chromosomes dividing; E, chromosomes moving toward centrosomes; F, diaster stage, 

 chromosomes at poles of nucleus, commencing constriction of cell body; G, daughter nuclei 

 beginning return to resting state; H, daughter nuclei showing monaster and wreath; 7, 

 complete division of cell body into daughter cells whose nuclei have returned to the resting 

 state. (After Bohm and von Davidoff.) 



In the first place, it is important to lay stress upon the differences between 

 vegetable and animal cells, first as regards their structures and next as re- 

 gards their functions. 



It has been already mentioned that in animal cells an envelope or cell wall 

 is by no means always present. In adult vegetable cells, on the other hand, 

 a well-defined wall is highly characteristic; this is composed of cellulose, 

 is non-nitrogenous, and thus differs chemically as well as structurally from 

 the contained protoplasmic mass. Moreover, in vegetable cells, figure 12, 

 B, the protoplasmic contents of the cell fall into two subdivisions: i, a con- 

 tinuous film which lines the interior of the cellulose wall; and, 2, a reticulate 



