2 DISTINCTIONS BETWEEN 
which regulate the distribution of plants over the surface of the 
earth at the present time. And 6, Palxontological or Fossil 
Botany is that which describes the nature and distribution of 
the plants which are found in a fossil state in the different 
strata of which the earth is composed. The first four de- 
partments are those only that come within the scope of the 
present work ; the two latter being of too special and extensive 
a nature to be treated of inthis Manual. There are also several 
departments of what may be called Applied Botany, which are 
founded on a knowledge of the above departments, such as 
Descriptive Botany, Vegetable Materia Medica, Agricultwral, 
Horticultural, and Economic Botany. To these special works are 
commonly devoted ; but, so far as the Properties and Uses of 
Plants are concerned, they will be particularly referred to in 
this work under Systematic Botany. 
DISTINCTIONS BETWEEN ANIMALS, PLANTS, AND MINERALS.— 
Botany being the science which treats of plants, it would natu- 
rally be expected that we should commence our subject by 
defining a plant. No absolute definition of a plant can, how- 
ever, be given in the present state of our knowledge of the 
organic world, neither is it probable that, as our knowledge 
increases, such will ever be the case ; for hitherto the progress 
of inquiry has shown that there is no distinct line of demarca- 
tion between plants and animals, the one passing gradually and 
imperceptibly into the other. Indeed, until quite recently, it 
was believed by many that there existed certain organisms 
which were plants at one period of their lives and animals at 
another. Thus De Bary, in the year 1859, described the 
germinating spores of Avthalium as producing naked, motile, 
protoplasmic bodies, which eventually coalesced to form amaoe- 
boid masses of protoplasm (plasmodiwm), which were destitute 
of a cell-wall, were able to creep over the surface of the 
substance upon which they were growing, and to take into 
their interior and digest solid matters, after the fashion of a 
true Ameba, of the animal nature of which there can be no 
doubt ; and so while in this stage he regarded A?thalium as an 
animal. After a time, however, the plasmodium becomes 
quiescent, divides into an immense number of small portions, 
each of which clothes itself with a wall of cellulose, and becomes 
a spore ; and in this later stage he regarded A’thalium as a 
plant. Butas the more recent researches of De Bary and others 
show that this amoeboid condition is of frequent recurrence in 
certain stages of many organisms, of the plant nature of which 
there can be no possible question, Athaliwm is now relegated 
to the Vegetable Kingdom alone. Nevertheless, even if the 
belief in the double nature (plant and animal) of certain orga- 
nisms does not now exist, naturalists are far from agreeing as to 
what in all cases shall be regarded as a plant or as an animal. 
Thus, while Stein looks upon such a complex structure as 
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