THE EARLIEST ANIMALS, 125 
portant fact that the egg of all animals, from those of sponges 
and worms up to those of the ant and man, is a simple cell. 
Thirdly, from the “single-cell” state arose the svmplest 
multicellular state, namely, a heap or a small community of 
simple, equiformal, and equivalent cells. Even at the present 
day, in the ontogenetic development of every animal egg- 
cell, there first arises a globular heap of equiformal naked 
cells, by the repeated self-division of the primary cell. (Com- 
pare vol. i. p. 190 and the Frontispiece, Fig. 3.) We called 
this accumulation of cells the mulberry state (Morula), 
because it resembles a mulberry or blackberry. This Morula- 
body occurs in’ the same simple form in all the different 
tribes of animals, and on account of this most important 
circumstance we may infer—according to the biogenetic 
principle—that the most ancient, many-celled, primary form 
of the animal kingdom resembled a Morula like this, and 
was in fact a simple heap of Amceba-like primeval cells, 
one similar to the other. We shall call this most ancient 
community of Amcebe—this most simple accumulation of 
animal cells—which is recapitulated in individual develop- 
ment by the Morula—-the Synameba. 
Out of the Synamcebe, in the early Laurentian period, 
there afterwards developed a fourth primary form of the 
animal kingdom, which we shall call the ciliated germ 
(Planzea). This arose out of the Synamceba by the outer 
cells on the surface of the cellular community beginning to 
extend vibrating fringes called cilia, and becoming “ ciliated 
cells,’ and thus differentiating from the inner and unchanged 
cells. The Synamecebee, consisted of completely equi- 
formed and naked cells, and crept about slowly, at the 
bottom of the Laurentian primeval ocean, by means 
