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stances. On this important subject, the reader may consult 
Mr. Gr. Gulliver’s able paper, On the Nature and Diagnostic 
Value of Eaphides,” pp. 568-582 of the Popular Science 
Keyiew for October, 1865. In addition to raphides, Mr. 
Gulliver has described other crystallme bodies that occur in 
abundance in a vast number of plants under the terms of 
sphseraphides ” and “ crystal prisms.” Nor are currents of 
water flowing from the oscules of sponges at times, when in a 
fresh state, sufficient in my mind to decide their animal charac- 
ter; because, in the masses of sponge, the presence of some 
parasitic animal, or infusorian, or other minute water-insect, 
may generally be detected. 
But I think it unnecessary to enumerate any more examples 
of characteristics that botanists might consider as tending, with 
great reason, to demonstrate an azoic, or non-animal, nature 
of these aquatic and remarkable lower organisms. 
This question, then, need not be continued any further, 
because I maintain that the limits between the animal and 
vegetable kingdoms are more or less artificial, and cannot be 
well determined ; for life in the lowest animal-being, and that 
in the smallest plant, cannot be sufficiently distinguished. But 
I have always held that the two chief characteristics of an animal 
are, without doubt, the muscular and nervous systems, which 
are wanting in a plant. I have already considered it to be 
useless any longer to dispute about the nature of sponges, and 
of the many like doubtful organisms. 
At the meeting at Oxford, in 1860, of the British Association, 
I communicated a paper, On the Distinctions of a Plant and 
an Animal, and on a Fourth Kingdom of Nature,” in which I 
stated that in order to place those organic beings which are of 
a doubtful nature in a fourth or an additional kingdom, I 
‘‘ suggested one under the title of the Primigenal Kingdom — 
Regnum Primigenum continens Protoctista, i. e. Protophyta 
et Protozoa, This would comprise all the lower creatures, or 
the primary organic beings,”* — Protonta, from irpSiTa, first, 
and ovra, beings ; or, as I preferred, the more expressive but 
less harmonious word, Protoctista, compounded of irptara, first, 
and KTicnd, created beings, both Protophyta and Protozoa. 
This fourth kingdom would of course include all the sponge- 
beings {Spongioctista), and the like anomalous lower ctista, 
creatures or organisms. 
As might have been expected, some slight objections were 
taken to these suggestions by the less scientific persons, and by 
those who had not carefully studied biology ; and they con- 
* See Report of the Thirtieth Meeting of the British Association,” 
p. 111. 
