116 



PLANT ANATOMY. 



I. THE UNFORMED NITROGEN- 

 OUS CELL CONTEXTS.-The main 

 coustituoiit is the Cytoplasm of tlic cell 

 body. It is generally viscid in consist- 

 ency, alknlino in reaction, and fills tlie 

 cuvilies of very young cells. After the 

 cells commonce to grow portions of the 

 CytophVsm are consumed in the building 

 up of the plant, and small vacuoles ap- 

 pear in it; these grow larger as the plant 

 increases until the cytoplasm may make 

 only a thin covering on the inside of the 

 cell wall. In this condition the term 

 Primordial Utricle has been applied to 

 it,^ and the vacuoles may become filled 

 with a transparent substance called the 

 Cell Sap, which may come to occupy the 

 major portion of the cell body. In still 

 older tissues, as in woody stems, the 

 cytoplasm may disappear entirely and 

 the cell cavity may become filled with 

 the cell sap, or be empty and dead, in 

 which case it serves as a mechanical 



support only. 



(Fig. 0.) Interspersed through it are 

 many small granules, the Microsomes, 

 whose function is still far from being 

 understood. 



The Cytoplasm is a very complex body, 

 but it will not be in place here to more 

 than outline its main characters.(a) 



It is the seat of the active life proc- 

 esses of the plant and represents the re- 

 sults of the active metabolism of the 

 plant tissues. 



2. por:med nitrogeneous 



CONTENTS, (a) The Cell Nucleus.- 

 This is a most important member of the 

 cell body. It is generally immersed in 

 the cytoplasm and lies, as a rule, to one 

 side of the center. It is to be found in 

 young growing tissues, but in older tis- 

 sues it may be absent. The pharma 

 cognocist rarely finds the nuclei in the 

 tissues of drugs that he is called upon 

 to investigate. Nuclei are generally sin- 

 gle in plant cells, but they may be in- 

 creased in number, as is to be found in 

 the bast cells of hops and nettles and 

 in some of the lacticiforous vessels of 

 poppy and euphorbia, and in many of the 

 lower orders of plant life, such as the 

 Alga) and Fungi. Nuclei are generally 



(a) Tbe student is referred to Reinke. 

 htudien liber das Protopla>?ma; Hertwig, 

 Die Zelle und die Gewebe, 1S92: for a more 

 complete statement of what is known about 

 this Interesting substance. 



small. The structure of the nucleus is 

 very complicated. In general it consists 

 of a nuclear membrane, quite deli- 

 cate, which surrounds the plasma of the 

 nucleus. In this plasma are a number 

 of substances as yet little understood. 

 The most important are those known as 

 Chromatine and Pyrenine, of which lat- 

 ter substance the nucleolus, a minute 

 granule found in the nucleus, is com- 

 posed, (a) 



In the nucleus the important process 

 of Cell Division has its origin. This 



^ Fig. 9. -ParenchjTna-cells from the central'cor- 

 tical layer of the root or FntillaHa imperialis; 

 longitudinal sections (x 550). A very voung cell 

 lymg close above the apex of the root, still with- 

 out cell-sap. B cells of the same description 

 about 2 mm. above the apex of the root; the cell- 

 sap .s forms separate drops In the protoplasm ;;^ 

 behind which lie walls of protoplasm; C tells of 

 the same description about 7—8 mm. above the 

 apex of the root; the two cells to the riffht below 

 are seen in a front view; the large cell to the left 

 below is m section; the cell to the right above is 

 onened by the section; the nucleus shows under 

 the mfluence of the penetrating water, a peculiar 

 appearance of swelling {x, y). 



process will be summarized under 

 Growth. 



(b) Aleurone Grains, These form the 

 reserve nitrogenous materials of the 

 plant in an analogous manner to the 



(a) Hertwig. Die Zelle und die Gewebe. 



