466 RICHARD ASSHETON. 
Again, a little further on, the same author expresses his 
views still more strongly. On page 175 he writes: “The 
ciliation of the ectoderm in the larva of Amphioxus continuing, 
as it does, long after the muscles have been fully differentiated, 
and when the cilia are therefore no longer required for purposes 
of locomotion, should be especially noted as evidence of a very 
archaic organisation. We shall find in the last chapter that 
the possession of a ciliated ectoderm is a prime characteristic 
of Balanoglossus and many of the lower worms (e.g. Nemer- 
tines). In none of the craniate Vertebrates is the ectoderm 
at any time ciliated.” 
Eycleshymer (4), discussing the question of the cause of the 
continuous rotatory movement of the vertebrate ovum, writes, 
on page 355: “ Clarke states that in Amblystoma puncta- 
tum the surface of the body is covered with cilia at the time 
the neural folds close, by means of which it keeps up its rota- 
tory motion. I have endeavoured to detect cilia by teasing in 
normal saline solution also by osmic acid fixation, but without 
success.” 
Clarke’s (3) actual words are— 
“The entire surface of the body is now” (i.e. when both 
the anal or caudal and cephalic ends are becoming more 
definitely indicated as they grow away and stretch out from 
the body of the embryo) ‘‘ covered with cilia, by aid of which 
it keeps up a horizontal rotatory motion upon its axis.” 
Balfour (1), on page 141, says of the newt that “ the skin is 
ciliated, and the cilia cause a rotation in the egg.” 
Again, of the frog the same author says, page 127: “ The 
outer layer of epiblast-cells becomes ciliated after the close of 
the segmentation, but the cilia gradually disappear on the 
formation of the internal gills. The cilia cause a slow rotatory 
movement of the embryo within the egg, and probably assist 
in the respiration after it is hatched. They are especially 
developed on the external gills.”’ 
Marshall and Bles (7) also notice the fact, page 42: “The 
whole surface of the tadpole is, as in the earlier stages, ciliated; 
