52 



BOTANY 



PAET I 



II. INTERNAL MORPHOLOGY 



(Histology and Anatomy) 



A. The Cell 

 1 . Structure of the Cell (^^) 



All plants and animals are composed of elementary organs called 

 cells. In contrast to animal cells, typical vegetable cells are surrounded 



by firm walls, and are thus sharply marked off 



from one another. In fact, it was due to the 



investigation of the cell walls that cells were 



recognised first in plants. An English micro- 



grai)her, Egbert Hooke, was the first to notice 



vegetable cells. He gave them this name in 



his Micrographia in the year 16G7, because of 



their resemblance to the cells of a honeycomb, 



and published an illustration of a piece of 



bottle-cork having the ai:)pearance shoAvn in the 



''""^I^Z^^J:^ ':^ ^dioining figure (Fig. 54). Robert _ HooKE, 



bottle-cork, which he de- howcvcr, was Only desirous of exhibiting by 



scribed as "Schematism ^^g^^ns of different objects the capabilities of 



or texture of cork." . t ji t t ht 



his microscope ; consequent!}^, the Italian, MAR- 

 CELLO Malpighi, and the Englishman, Nehemiah Grew, Avhose Avorks 

 appeared almost simultaneously a few years after Hooke's Micrographia, 

 have been regarded as the founders of 

 vegetable histology. The living contents 

 of the cell, the real body or substance, 

 was not recognised in its full significance 

 until the middle of last century. Only 

 then was attention turned more earnestly 

 to this studj% which, based on the Avorks 

 of Meyen, Schleiden, Hugo v. Mohl, 

 Nagelt, De Bary, Ferdinand Cohn, 

 Pringsheim, and Max Schultze con- 

 tinues to develop. 



If an examination be made of a thin 

 longitudinal section of the apex of a stem 

 of a phanerogamic plant, \nih a higher 

 magriif}-ing power than that used in the 

 previous investigation (Fig. 17) of the vegetative cone, it will be seen 

 that it consists of nearly rectangular cells (Fig. 55), which are full of 

 protoplasm and separated from one another by delicate walls. In 



Fig. 50. —Embryonic cell from the 

 vegetative cone of a phanerogamic 

 ])lant. k, Nucleus ; lew, nuclear 

 membrane ; n, nucleolus ; cy, cyto- 

 plasm ; ch, chromatophores ; m, cell 

 wall. (Somewhat diagrammatic, x 

 circa 1000.) 



