1891.] Some Recent Papers on Earthworms. 5 
one of the anterior myoblasts, each budding off its corresponding 
row. In next stage observed there were present two anterior 
myoblasts. The connection between these was not made out, 
but Bergh thinks from certain features that the new one was 
budded from the earlier one, and that the first to appear corresponds 
to Wilson’s inner nephroblast, the second to his lateral teloblast. 
A later stage showed the budding off from the inner myoblast of 
the middle myoblast, and still later this was seen to form a row 
which becomes insinuated between the other rows. All of these 
cells are as yet ectodermal, and the neuroblasts and the neural 
rows are the first to become covered by the ectoderm. Appar- 
ently the bands are solely derived from the teloblasts, and the 
ectoderm contributes nothing further to this growth. 
Bergh describes a new element in the nervous system as a plexus 
of nerve cells and nerve fibres, which develop along the middle of the 
ventral surface between the neural rows. In the ectoderm of this 
region, just beneath the ciliated line, are certain uni- and bipolar 
cells, the processes of which run lengthwise of the animal, and form 
a temporary nervous system before the permanent nervous system 
has begun the development of nerve fibres. These cells are re- 
garded as arising independently of the neuroblasts from the ecto- 
derm, the fact that they extend behind the neuroblasts being strong- 
ly confirmative of this view. Later this plexus is included in the 
permanent nervous system, while the ciliated cells are resorbed, 
and, contrary to Kleinenberg’s view, do not form part of the regu- 
lar ectoderm. Bergh suggests that the ventral median multipolar 
elements described by Friedlander may originate from this plexus, 
Hatschek’s median invagination does not exist in Lumbricus. 
The three remaining germ-bands, says Bergh, have nothing to 
do with the formation of the nephridia, and at no place do they 
project inwards, as described by Wilson, into the inner muscle 
plate. They rather spread out between ectoderm and the product 
of the hinder myoblast, and give rise to the circular muscles of 
the adultworm. These muscles are first formed ventrally, and 
later reach the dorsal surface. 
The nephridia are, on the other hand, derived wholly from the 
inner mesoderm, the first portion to be distinguished being the 
