32 
W. F. I’UHCEU.. 
iiimniierable tiny cliitinous rods, which are firmly soldered to 
each membrane and distributed over their entire inner sur- 
faces (.s. 1, figs. 17 and 18). The ante-chamber is also provided 
Avith a smooth cnticnla fig. 18), except in the dorsal 
growing ]>art {pulm. 'prol.). 
The walls of the cliitinous saccules are lined on one(thebasal) 
surface with a thin layer of protoplasm, which is, of course, 
the matrix, and althoug’h this layer may become very thin (as, 
for instance, in Agelena laby rin thica), it is always dis- 
tinctly recognisable at this stage. Locy could not trace the 
protoplasm on the chitin away from the columns in Ag-elena 
naevia, ivhile Jaworowski (’94) describes these columns as 
atmeboid in shape, sending out processes over the surface 
of the chitin to connect with those of neighbouring cells of 
the same epithelium. 
The moulting' of the lung-books. — It is well known that at 
each monlt of the young spider the entire cliitinous lining of 
both the ante-chamber and saccules is cast off (Menge, ’51, 
p. 22; W. Wagner, ’88, p. 315), and that the ventral walls of 
the latter produce the innumerable free spines on the surface 
of the cnticnla (W. Wagner, ’88, p. 314). A’’arious points of 
interest still remain to be described in connection wdtli the 
growth at monlting-.^ 
Already at the time of hatching we find the saccules pre- 
paring for the first post-embryonic moult, although the latter 
does not take place until nearly a week later. The epithelia 
of each saccule expands in a medial, as well as in an anterior 
direction, considerably beyond the corresponding edges of its 
primitive cliitinous lining, while the lateral and posterior 
edges I'emain stationary. 'I’he enlarged saccule thus created 
then secretes over its interior surface a new cuticula forming 
a, second cliitinous saccule (/., fig. 34), Avhich encloses the 
one first formed (.v.) and differs from it in structure. For its 
ventral membrane bears over that part of its area which is 
co-extensive with the primitive cuticnlar saccule (.s.) nume- 
' The fullowing' remarks on this suhject apply equally to Attiis 
floricola, Agelena lahyrinthica, and Tegenaria atriea. 
