(g) 



Figure 2-1. Plant and Animal Cells Exhibiting Differences in Shape: 

 (a) oligodendrocyte from 5-day culture of rat brain tissue (corpus cal- 

 losum); (b) unfertilized animal egg cell of starfish; (c) bacterial cells 

 {Azobacter species); (d) giant multipolar motor nerve cells from ox spinal 

 cord; (e) unicellular animal organism {Ameba species); (f) grouping of 

 alga cells (Spirogyra); (g) nucleated erythrocytes of bird; (h) guard cells 

 associated with leaf stomata. (Fig. (a) from Lumsden, C. E. and Pomerat, 

 C. M., 1951. "Normal Oligodendrocytes in Tissue Culture," E.xptl. Cell Res., 

 2, Fig. 5, p. 109. Courtesy of Dr. C. M. Pomerat, Pasadena Foundation for 

 Medical Research. Figs, (b) through (h), courtesy of General Biological 

 Supply House, Inc., Chicago, 111.) 



In addition to the nucleus, the cytoplasm of the cell usually contains a 

 number of distinct bodies or structures that presumably carry out one or 

 more rather specific functions (Figure 2-2). These structures, which are 

 discussed in Chapters 3 and 4, are frequently classified according to 

 whether they are living (organelles) or dead (inclusions). Our lack of 

 knowledge concerning ontogeny and function of many of them makes 

 such a classification of dubious utility. For purposes of discussion, the 

 components of the cytoplasm may be broadly classified, on the basis of 

 light and electron microscope studies, as follows: (1) mitochondria, 

 (2) plastids, (3) lysosomes, (4) endoplasmic reticulum, (5) "micro- 

 somes," (6) cytoplasmic matrix, (7) Golgi complex, (8) cell mem- 

 brane, (9) vacuoles, and (10) cytoplasmic inclusions. 



Although attempts to apply the methods of chemical analysis to living 

 matter are almost as old as organic chemistry, it is only in recent years 

 that major advances have been made in this direction. Quite apart from 

 the innate complexity of protoplasm is the technical difficulty of obtain- 

 ing analytic samples in "pure" form. The relative amounts of various 



GENERAL MORPHOLOGY AND CHEMISTRY OF THE CELL / 11 



