APPENDIX B 



ON THE DIFFERENCES BETWEEN THE CELLS OF THE 

 HIGHER PLANTS AND THE HIGHER ANIMALS 



It is probable that in certain points the cells of the higher 

 animals and the higher plants are not strictly homologous with 

 each other. 



Botanists distinguish three main types of elementary structure 

 among plants, their differences arising out of differences in the 

 method of cell-division practised (Fig. 16). In the first type 



a 



Fig. 16. Diagram to show the three main types of elementary 

 structure found in plants, (a) coccoid, (b) filamentous, (c) 

 coenocytic. In each case is shown the sum of the changes 

 following upon binary division of the nucleus of a single cell. 



(Coccoid), the entire cell, with its cell-wall, divides into two 

 similar and quite separate halves. This is practised, e.g., by 

 unicellular Algae. In the second type (Filamentous), the cell- 

 body (cytoplasm and nucleus) divides as before, but the cell-wall 

 does not divide ; instead, an entirely new party-wall is laid down 

 between the two cell-bodies, and in this partition small apertures 



