3 BOTANY. 



colorless achromatin {nuclear-Tiyaloplasm) making up the 

 bulk of the nucleus; (b) a network of minute fibres (Fig. 

 2,/); (c) minute granules of chromatin in the network 

 (Pig. 2, cJin); and (d) one or more rounded bodies, the 

 nucleoles, lying in the achromatin (Figs. 1 and 2, ne). 



Fig. 1.— a young plant-cell mag- 

 nified about lOOO diameters, w, 

 cell-wall; cy, cytoplasm; n, nu- 

 cleus ; ne, nucleole ; ce, centro- 

 spheres ; cTio, chromatopliores. 

 (From Strasburger.) 



i chn 



Fig. 3.— Nucleus from the em- 

 bryo-sac of Fritillaria, magnified 

 1000 diameters, ne, nucleoles; /, 

 fibres of fibrillar network; chn, 

 ' chromatin granules ; C6, centro- 

 spheres, each containing a darker 

 centrosome. (From Strasburger.) 



(3) Two small rounded bodies, the centrospheres, which 

 are usually just outside of the nucleus, lying in the cyto- 

 plasm (Figs. 1, 2, ce). They are known also as the "di- 

 rective spheres," and the granular centre of each is the 

 centrosome. 



(4) A number of small usually rounded bodies lying in 

 the cytoplasm, and normally colored green (more rarely 

 yellow or reddish), are known as the cJiromatophores (Fig. 

 1, cho). 



3. Although protoplasm is so abundant, its exact chemi- 

 cal composition is not known. It appears to be a mixture 

 of seTeral chemical compounds, and contains carbon, hy- 

 drogen, oxygen, nitrogen, sulphur, besides others of less 

 importance. Nitrogen is always present. By delicate 



