a ee ee Se E E T ET EEEE ee 
1885.]+ Comparative Physiology and Psychology. 15 
the cilia were organs of locomotion while the body remained 
sensitive. We may regard the cilium as formed of dead material 
in the main, Dallinger and Drysdale’s monad rejected it in eating 
its companion. This would shadow forth the possibilities of a 
set of ciliary vibrations becoming known to the animal as tactile 
locomotory, differing from, though ministering to, hunger sense, 
and a change in the aggregation of the cell granules would fol- 
low. When the cell granules moved in keeping with the ciliary 
motions either the locomotory memory or act was aroused, if in 
accordance with hunger movements then the memory of hunger 
was aroused and this could react on the cilia to move them. 
When the ectoderm reached a stage of hardening admitting of 
no more strain upon it, the central contents transuded by some 
means, probably temporary rupture. The gaseous and watery 
contents escaped and the animal collapsed into the gastræada 
stage. The enteric cilia still remain as originally developed, but 
of course changes between ectodermal and endodermal experi- 
ences would differentiate the two areas. The inner remained 
subject to constant encounters, or nearly so, and the outer had 
the brunt of every change. : 
The accelomotous Turbellaria appear to me to be more of an 
aberrant type not in our phylum, many of the forms have under- 
gone much development. The delamination origin of the gas- 
trula stage could be one of those ontogenetic short cuts often 
made in copying phylogenesis, the end attained being the same. 
The Scolecid presents the most evident progress toward 
development in the vertebrate direction. Its ccelom contains the 
first nutrient fluid allied to blood, but its circulation is not estab- 
lished. The denudation of the useless external cilia, though 
occasionally developed into stiff sete, in a turbellarian follow the 
locomotory process, changing to that characteristic of worms, 
elongation and contraction of the body length. Hubrecht’s 
Pseudonematon illustrates this movement, through the alternate 
contraction of longitudinal and circular muscles with a plexiform 
nervous system between. The motion is in some respects simi- 
lar to the flow of amceba granules forward into an arm, but organ- 
ization has restricted this to a to-and-fro motion. The shape of 
the body rendering this the easiest mode of progress, the sum of 
the life activities act in least resistant lines to elongate and then 
contract the worm. Cause and effect exchange places in the circu- 
