530 MICROSCOPIC FORMS OF VEGETABLE LIFE THALLOPHYTES 



CHAPTER VIII 



MICROSCOPIC FORMS OF VEGETABLE LIFETHALLOPHYTES 



THOSE who desire to make themselves familiar with microscopic 

 appearances, and to acquire dexterity in microscopic manipulation, 

 cannot do better than educate themselves for more difficult inquiries 

 by the study of those humblest types of vegetation which present 

 organic structure under its most elementary aspect. And such as 

 desire to search out the nature and conditions of living action will 

 find in the study of its simplest manifestations the best clue to the 

 analysis of those intricate and diversified combinations under which 

 it presents itself in the highest animal organisms. For it has now 

 been put beyond question that the fundamental phenomena of life 

 are identical in plants and in animals, and that the living substance 

 which exhibits them is of a nature essentially the same throughout 

 both kingdoms. The determination of this general fact, which forms 

 the basis of the science of BIOLOGY, is the most important result of 

 modern microscopic inquiry ; and the illustration of it will be kept 

 constantly in view in the exposition now to be given of the chief 

 applications of the microscope to the study of those minute proto- 

 phytes (or simplest forms of plant-life) with whose form and structure, 

 and with whose very existence in many cases, we can only acquaint 

 ourselves by its aid. 



It was formerly supposed that living action could only be 

 exhibited by organised structure. But we now know that all the 

 essential functions of life maybe carried on by minute 'jelly-specks,' 

 in whose apparently homogeneous semi-fluid substance nothing like 

 ' organisation ' can be detected ; and, further, that even in the very 

 highest organisms, which present us with the greatest variety of 

 * differentiated ' structures, the essential part of the life-work is clone 

 by the same material these structures merely furnishing the 

 mechanism (so to speak) through which its wonderful properties 

 exert themselves. Hence this substance, 1 known in vegetable 

 physiology as protoplasm, but often referred to by zoologists as 



1 Attention was drawn in 1835 by Dujardin (the French zoologist to whom we owe 

 the transfer of the Foraminifera from the highest to the lowest place among inverte- 

 brate animals) to the fact that the bodies of some of the lowest members of tlie 

 animal kingdom consist of a structureless, semi-fluid, contractile substance, to which 

 he gave the name sarcode (rudimentary flesh). In 1851 the eminent botanist Von 

 Molil showed that a similar substance forms the essential constituent of the cells of 

 plants, and termed it protoplasm (primitive plastic or organisable material). And in 

 1868 it was pointed out by Prof. Max Schultze, who had made a special study of the 

 rhizopod group, that the ' sarcode ' of animals and the ' protoplasm ' of plants are 

 identical. See his memoir Ueber das Protoplasma der Rliizopodcn itnd Pflanzen- 

 zellen. 



