326 Dr. T. Margé on the Classtfication 
the best attainable, and we may be satisfied with the result of 
our labour if, supported on the morphological and embryolo- 
gical facts already collected and ascertained, and considering 
the known paleontological forms, we endeavour with our full 
knowledge and conscientiously, by a systematic grouping of 
the animal kingdom, to express, to the best of our power, the 
relations existing between the different animals, as well as 
the natural position of the groups and their individual 
members. 
Now that we have discussed in detail the general principles 
of classification, as well as the precautions necessary for a 
natural grouping of animals, I may be permitted, as a small 
contribution towards the construction of a phylogenetic 
system, to expound my views as to the relationships of the 
different groups, although only tentatively, in the form of a 
genealogical tree (see p. 334). In the grouping of the dif- 
ferent stems, as well as in their relations to one another, this 
agrees in many respects with others, but nevertheless, as 
regards certain ramifications and groups of the genealogical 
tree, it differs, not unessentially, from other similar attempts. 
The following remarks may serve to explain and elucidate 
our subject. 
First of all I must notice particularly that, although the 
denominations “ Protozoa’ and ‘ Metazoa’’ are almost uni- 
versally employed in modern zoology for the two principal 
groups of the animal kingdom, I think it would be better to 
call the former “ Protoplastica,” as a word which expresses 
more accurately and better the nature of these lowest animals ; 
and the latter “ Blastodermica.”’ In these latter the body 
never consists of one or more homogeneous protoplasmic cells, 
but is always composed of heterogeneous cells and tissues, 
which tissues are originally produced from two different 
blastodermic cell- or germ-layers, namely, from the primitive 
ectoderm and. entoderm. 
The animals which are developed with such a blastoderm 
(Blastodermica) divide, from a phylogenetic point of view, 
into two main branches. 
The smaller main branch is represented by those blasto- 
dermic animals which, remaining at a low stage of develop- 
ment, possess only a simple primitive nutritive cavity, formed 
by the ectcderm alone, without any trace of a cceloma. ‘These 
lower Metazoa (Blastodermica), which are nourished by 
a primitive nutritive cavity (archenteron), we therefore name 
“ Archentera.” 
