ot DEVELOPMENT #35 
within themselves, they develop a .temporary stomach and a 
large sucking organ, and become for a time independent sucking 
animals, imbibing the fluids in the common sac, and arranged 
around its circumference with their mouths directed towards the 
centre. Subsequently a second embryonic stage is entered upon, 
the sucking organ being discarded, and the albuminous matter 
which the larva has imbibed being treated anew lke the original 
yolk of the egg. 
{t is an interesting fact that in this second embryonic stage a 
well-marked ‘ tail” or post-abdomen is formed, and the ganglonic 
nerve-masses increase in number, a cerebral mass being followed 
by eight pairs of ganglia in the body and eight in the tail. 
C 
Fic. 224.—Three stages in the development of Chelifer. 
A, Segmenting ovum ; B, embryo, with post-abdomen, maximum number of ganglia, 
and developing sucking apparatus ; C, larva. (After Barrois. ) 
Subsequently a great concentration takes place till, besides the 
cerebral mass, only five closely-applied pairs of ganglia remain, 
corresponding to the pedipalpi and the four pairs of legs. | More- 
over, the first pair advances, so as to le on the sides of, and not 
behind, the oesophagus. 
There are two ecdyses or moults during development, a partial 
moult, concerning only the ventral surface of the “ pro-embryo” 
as it assumes the larval form, and a complete moult at the final 
stage, before emergence from the incubating sac. 
At the end of winter the mother cuts a hole in the silken 
web, and the young brood issues forth." 
1 For the embryology of Chernetidea, see J. Barrois, ‘‘ Mém. sur le développement 
des Chélifers,”” Rev. Swisse de Zool. ii., 1896. Metschnikoff, Zectschr. wise. Zool. 
xxi., 1876, p. 514; and Vejdovsky, Congrés zool. international de Moscow, 1892, 
p. 120, may also be consulted. 
