■3 



B0TAN7. 



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



tlons arb 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 liiglier 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 

 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 they are to be re- 

 garded as prodticts rather than 

 proper constituents of protoplasm. 



Fig. 1.— A little more than half of 

 -a longitudinal section of the apex of , ^ -r,' j. i , . t i i 



a young root of the Indian corn. W " ^t^r makes up a considerable 



The part above s Is the body of the part of the bulk of ordinary protoplasm, 

 root, that below n is the root-cap ; j . , , , . 



«, thick outerwall of theepidermis; ana IS much more abundant m its 



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

 cells ; g, a young vessel ; s, i, inner -, , v.>juuii,iuuo. 



younger part of root-cap ; o, o, out- In the protoplasm of PuUgo varians 

 Sachs •""^ °' root-cap.-After (q^^ 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. 



(6) 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 iiber Protoplasma," 1876. 



