REVIEW OF SPENGEL’S MONOGRAPH ON BALANOGLOSsUS. 415 
careful investigations of Bateson are set aside when they do 
not happen to tally with Professor Spengel’s theories. Bate- 
son’s researches established the following points of resemblance 
between the development of the larva he investigated and that 
of Echinoderms. (1) The blastopore closes in the position of 
the futureanus. (2) The entire alimentary canal from mouth 
to anus is of endodermic origin. (8) The mesoderm originates 
as archenteric diverticula. In the trochosphere, on the other 
hand, the blastopore when it persists becomes the mouth, there 
is a stomodzeum and a proctodzeum, and the mesoblast originates 
by budding from two large cells in the neighbourhood of the 
blastopore. 
Now Spengel says with regard to the first of these differences, 
“T cannot put it otherwise, in spite of Bateson’s researches, 
than that we are still ignorant of the earlier stages of 
development ;”’ and “ Bateson’s statements as to the blastopore 
do not appear to me to be more trustworthy than those of 
others who have observed the persistence of the blastopore as 
anus in other animals.” Bateson’s figures, however, give 
demonstrative proof that his statement is correct. The Tornaria 
larva has, as we know, a longitudinal ciliated post-oral band, 
and behind this a perianal one. Now in Bateson’s larva this 
perianal band is the only one present, and it appears very early. 
In one of his figures we see it appear on an almost spherical 
gastrula and in the centre of it we see the disappearing blasto- 
pore. What further proof Professor Spengel would desire is 
not quite clear tome. With regard to the absence of stomo- 
deeum and proctodzum, he says, “‘In the absence of figures it 
is impossible to form any opinion as to the value of Bateson’s 
statements.” Now the mouth and anus do not appear till after 
gill slits and notochord have been formed, and to demand 
figures before accepting results about which it is difficult to 
imagine that a worker who used modern methods, like 
Bateson, could be mistaken, only exhibits the amount of 
prejudice which has clouded Professor Spengel’s mental] vision. 
With regard to the origin of the coelomic cavities as 
endodermic pouches, Spengel complains that the transverse 
