BOTANY. 



differs from that of animals in its secretions. And yet these secre- 

 tions are not strictly confined to plants ; cellulose, starch, chlorophyll, 

 and other products of vegetable protoplasm formerly regarded as pe- 

 culiar to plants are now known to occur in undoubted animals. Botanists 

 and zoologists have labored long in vain to discover absolute differences 

 between the animal and the vegetable kingdoms, between the higher 

 plants and the higlier animals there are great and constant differences,- 



in none of the higher animals, for ex- 

 ample, is chlorophyll produced ; but 

 in the lower orders of both kingdoms 

 not one of the differences observed to 

 hold between the higher plants and 

 ij-t animals exists. 



2. The exact chemical compo- 

 sition of protoplasm has not hith- 

 erto been made out, but it is 

 known to be an albuminous, 

 watery substance, combined with 

 a small quantity of ash. It is 

 probably a complex mixture of 

 chemical compounds, and not a 

 single compound. It contains at 

 some time or another all the chem- 

 ical constituents of plants. Oil, 

 granules of starch, and other or- 

 ganic substances are frequently 

 present in it, but the} r are to be re- 

 garded as products rather than 

 proper constituents of protoplasm. 



Fig. 1. A little more than half of 

 a longitudinal section of the apex of 

 a young root of the Indian corn. 

 The part above s is the body of the 

 root, that below it is the root-cap ; 

 v, thick outer wall of the epidermis; 



() Water makes up a considerable 

 part of the bulk of ordinary protoplasm, 

 and is much more abundant in its 



young pith-cells ;/, young wood- active than in its dormant conditions. 

 cells ; a. a young vessel ; s. i, inner _ , , _, , . 



younger part of root-cap ; a, a, out- In the protoplasm of Fuhyo vanans 



Sachs Par * f root>6ap -- After (one of the Slime Moulds) just before 



the formation of its spores there is 70 



per cent of water ; in dry seeds, on the other hand, the amount is not 

 more than about 8 to 10 per cent. 



(b) As to its molecular constitution, Strasburger holds* that proto- 

 plasm is composed of minute solid particles (not, however, of a crystal- 

 line form), separated from each other by layers of water (see Cell-wall, 



* " Studien uber Protoplasma," 1876. 



