Septembee 20, 1895.] 



SCIENCE. 



371 



ments and transformations of the two most 

 characteristic elements of organic structures, 

 carbon and nitrogen, are a little better 

 known. Some progress has been made in 

 tracing the steps by which the simple mole- 

 cule of carbon dioxide derived from the 

 atmosphere is built up into the complex, or- 

 ganic molecule of starch. But the further 

 process by which the starch molecule com- 

 bines with others to form the most complex 

 and important of all plant substances, pro- 

 toplasm, is yet an almost complete mystery. 

 The story of the progress of discovery in as- 

 certaining the means by which plants get 

 their nitrogen is a fascinating one, and is 

 not yet ended. These matters in part lie 

 at the very foundation of the most funda- 

 mental of industi'ies, agriculture. Inten- 

 sive farming, and the highest success in the 

 raising of all kinds of crops, is greatly pro- 

 moted by a knowledge of the nutritive pro- 

 cesses in plants. The botanists who thirty- 

 five years ago demonstrated that carbon 

 was taken into the plant through the leaves, 

 and not to any material extent through the 

 roots, struck a theme that revolutionized 

 agricultural practice and added greatly to 

 the wealth of the world. The more recent 

 discovery of the connection of symbionts 

 with leguminous and some other plants, by 

 which the abundant supply of nitrogen in 

 the air is converted into food available for 

 higher plants, has also greatly affected agri- 

 cultui-al practice. The whole subject of 

 the nutrition of plants is so bound up with 

 intelligent farming and all manner of plant 

 cultivation that advancement of this part of 

 physiology means an increase in material 

 prospei-ity as well as in scientific knowledge. 

 Ample provision for its prosecution would 

 be a valuable investment for any people, 

 and particularly so for the people of these 

 United States. 



There are many ways in which j^lants 

 show similar physiological processes to those 

 of animals ; and plants being simpler in or- 



ganization, their study may often be made 

 to promote a knowledge of animal phj^si- 

 ology. The greatest similarity between the 

 two kingdoms lies in various phases of nu- 

 trition, respiration and reproduction. The 

 greatest divergence is to be found in the 

 manifestation of irritability. Those funda- 

 mental processes upon which being and con- 

 tinued existence depend are much the same 

 throughout animate nature, but the pro- 

 cesses by which the organism communicates 

 with the world outside of itself, and through 

 which it is enabled to adjust itself to en- 

 vironmental conditions, the processes which 

 in their highest development are known as 

 sensations, have attained great differentia- 

 tion, running along essentially different 

 lines of development. The prevalent vicAV 

 that plants occupy an intermediate position 

 between the mineral and the animal king- 

 doms is not true in any important respect. 

 Neither is it true that the faculties of ani- 

 mals, especially of the lower animals, are 

 foreshadowed in plants. ISTo just concep- 

 tion of animate nature can be obtained by 

 conceiving it to lie in a single ascending se- 

 ries. It constitutes two diverging and 

 branching series, like the blades and stems 

 in a tuft of grass, which we may assume 

 have been derived from a common germ. 

 There are two fundamental characters 

 which manifested themselves early in phy- 

 logenetic development, one structural and 

 one physiological. The structural character 

 of the histologic integument of the organ- 

 ism, in animals soft and highly elastic, in 

 plants firm and but slightlj^ elastic, gave 

 rise to the two series of forms, structurally 

 considered, which we call animals and 

 plants. The phj'siological character of free 

 locomotion for most animals and a fixed 

 position for most plants determined the 

 line of separation for the development of 

 those powers of the organism classed as ir- 

 ritability and sensation. So great have 

 been the differences which these funda- 



