of Edinburgh, Session 1883-84. 
277 
mineral — that disastrous philosophic and scientific aberration ” 
bequeathed by the alchemists to the last encyclopaedist of Gesner’s 
school, and unfortunately adopted and sanctioned by Linnaeus, has 
not of course been seriously adopted by any philosophical biologist 
of the century ; hardly the narrowest specialist among zoologists or 
botanists any longer seriously doubts the validity of the classifica- 
tion of natural objects into two groups only — inorganic and organic — 
yet, at the same time, the vicious results of the earlier dogma still 
everywhere survive, and indeed necessarily so. For the unity of 
plant and animal life requires morphological demonstration, and that 
more precise than has hitherto been afforded by merely separating 
off the lowest plants and animals into a third still heterogeneous 
group of Protista. This deficiency is supplied by the present argu- 
ment, for if the Protista, the Yegetabilia and the Animalia have 
indeed been correctly interpreted, as somewhat variously specialised 
cell-alggregates derived from an ancestral Protomyxomycete, their con- 
solidation into a single kingdom is a matter of course. In one edition 
of the Systemd Naturce, Linnaeus clearly recognised the fundamental 
unity of plants and animals, by uniting them in opposition to the 
non-living wmrld {Conserta) as Organisata, and this term it is accord- 
ingly not only convenient, but necessary forthwith to revive. 
9. Morphologicat Classification of Animal Tissues. — Histologists 
are accustomed to recognise three main groups of animal tissues. 
Thus Cornil and Panvier"^ distinguish (1) connective tissues, in 
which the cells are united and separated by a substance of charac- 
teristic form and properties; (2) muscular and nervous tissue, in 
which the cells have undergone extraordinary modifications, both 
structural and functional; (3) epithelial tissue, in which the cells 
possess a regular and constant evolution. 
In this classification, however, as in so many others, morphological 
and physiological characters are not kept distinct. In briefly 
glancing at morphological characters only, it is evident we may best 
approach the problem by first noticing some of those cellular trans- 
formations made known by the recent students of embryology. 
Histogenesis must underlie histology. 
An ovum is at first a naked amoeboid cell, then assumes tho 
encysted state, then segments into an aggregate of amoeboid cells ; this 
* Manuel cC Histologic Tatliologigue, i. p. 11, Paris, 1881. 
VOL. XII. 
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