DIV. I MORPHOLOGY 11 



vegetable cells. He gave them this name in his Micrographia in the year 1667, 

 because of their resemblance to the cells of a honeycomb, and published an illus- 

 tration of a piece of bottle-cork having the appearance shown in the adjoining 

 figure (Fig. 1). The Italian, MARCELLO MALPIGHI, and the Englishman, NEHE- 

 MIAH GREW, whose works appeared almost simultaneously in 1671, a few years 

 after HOOKE'S Microyraphia, were the true founders of vegetable histology. The 

 living contents of the cell, the protoplast, was not recognised in its full significance 

 until the middle of last century. Only then was attention turned more earnestly 

 to the study of cytology, which, based on the works of SCHLEIDEN, HUGO v. MOHL, 

 XAGELI, FERDINAND COHN, and MAX SCHULTZE, was especially advanced by 

 STRASBUEGER. 



II. THE LIVING CELL CONTENTS. THE PROTOPLAST ( 4 ) 



*- 



A. The Constituent Parts of the Cell 



If a thin longitudinal section of the growing point of the stem of 

 one of the higher plants is examined under the high power of the 

 microscope it is seen to consist of nearly rectangular cells (Fig. 2), 

 which are full of protoplasm and separated from one another by 

 delicate walls. If sections in various directions through the apex 

 are compared, the conclusion is reached that 

 the cells have the shape of small cubes or 

 prisms. 



In each of the cells a spherical or oval 

 body, which fills a large part of the cell 

 cavity, is distinguishable. This body (k) 

 is the NUCLEUS of the cell. The finely 

 granular substance (pi) filling in the space 

 between the nucleus (k) and the cell wall 



(ro) is the cell plasm, or CYTOPLASM. In the FIQ 2 ^ cell from the 

 cytoplasm there are to be found around the root-tip of the Oat. fc. Nucleus; 



nucleus a number of Colourless and highly to, nuclear membrane ;n,nucle- 



refractive bodies : these are the PLASTIDS or 5**Ki " 



CHROMATOPHORES (ch). THE NUCLEUS, what diagrammatic, x about 

 CYTOPLASM, AND CHROMATOPHORES ARE 1500 ' After LEWITZKT.) 

 THE LIVING CONSTITUENTS OF THE CELL. 



They form together the protoplasm of the living cell body or PROTO- 

 PLAST. The nucleus and the chromatophores, which are always 

 embedded in the cytoplasm, may be regarded as organs of the 

 protoplast since they perform special functions. It is true that the 

 particular functions of the nucleus are unknown, but it is certain that 

 the interaction of nucleus and cytoplasm is necessary to maintain the 

 life of the cell. In the lowest plants (Cyanophyceae and Bacteria) 

 such a division of labour in the protoplasm is not certainly proved, the 

 existence of the nucleus being still a matter of dispute ( 5 ). Chromato- 

 phores are wanting in the Bacteria and Fungi as in all animal cells. 



