94 
Proceedings of the Eoyal Society of Edinburgh. [Sess. 
Fig. 8. Section cut longitudinally through a young papilla of about fourteen days’ 
growth, X 50 diars. The cavity (vc) has increased, and the nerve {n) is seen 
sending out fibres to the growing tip {gt). An invagination of the outer chitinous 
coat at {{) shows the beginning of segmentation and tendon formation. 
Plate III. 
Fig. 9. Longitudinal section of a papilla of about three weeks’ growth, x 50 diars. 
Segmentation is now advanced, and constrictions (c' and e”) represent the joints of 
the future limb. Cells budded off from the epidermis at the growing tip have 
come to lie within the cavity as muscle-masses (mm), and the nerve is seen running 
upwards {n). 
Fig. 10. Section through muscle-mass, showing embryonic fibres in longitudinal 
section, x 300 diars. The nuclei of cells of the muscle-masses have lined up outside 
the fused cytoplasm (n), and longitudinal striation indicates the formation of fibrillse 
{fih). {t) is the tendon of attachment for the new fibres. 
Fig. 11. This photograph is one of the same field as fig. 10, but the focus is 
altered to show cross striation in the young fibrillm (/). 
Fig. 12. Transverse section through a fully developed muscle-mass, x 300 diars. 
The new muscle-fibres, cut transversely, show nuclei outside {n), and fibrillae as dots 
within them (/). The loose investment of connective tissue, which, after moulting, 
fits tightly round the fibres, represents the new sarcolemma (sar). It will be 
noticed that it has no nuclei. 
Plate IV. 
Fig. 13. The lobster in this photograph autotomised its right cheliped and two 
first walking legs on 16th April 1914. By the middle of August of the same year 
it presented the appearance shown in the photo ; i.e. papillae had grown out from 
the bases of the lost legs. These are marked {jp), (p), and (p"). 
Fig. 14. This photograph represents the appearance of the same lobster as that 
shown in fig. 13, immediately after it had moulted (1st September 1914). (ch), 
(wlr), and (ivll), are the regenerated appendages expanded from the papillae (^), 
(p), (p"), respectively, in fig. 13. 
Fig. 15. These outline drawings represent in life size the lost cheliped and the 
regenerations of the lobster shown in figs. 13 and 14. (P) is the papilla, (R) the 
regenerated limb after moulting, and (N) the lost limb. 
Fig. 16. These photographs show the shore crab with its empty shell referred to 
in part third of the observations. In A, the shell, pieces of black paper have been 
placed behind the empty papillae-envelopes. The latter are marked (a), (b), (c), 
and (d). When moulting occurred the papillae were immediately expanded, and 
{a'), {b'), (c ), and (d') in B are the new limbs thus formed. 
(Issued separately April 6 , 1915 .) 
