422 
W. X. F. WOODLAND. 
ponderant. Concerning the origin of the end-sac, the evidence 
is not so one-sided. The statements of Waite, confirming 
those of Lebedinsky and Boutchinsky, are quite definite as to 
the origin of the end-sac in a distinct mass of mesoderm cells, 
and the secondary junction of the end-sac with the ecto- 
dermal kidney and duct. On the other hand, Grobben figures 
the end-sac cells as forming the upper extremity of the simple 
invagination in the early development of the gland, just as I 
have figured these same cells in my drawing of the youngest 
stage of the Squilla gland — there is no separate origin of the 
end-sac here — and Boutchinsky merely asserts that the deep 
end of the ectodermal invagination becomes surrounded by 
mesoderm cells — a statement which may have resulted from 
a mistaken conception of the origin of the ^‘'mesoderm cells. 
Further, Waite’s supplementary argument for the separate 
origin of the end-sac based upon the entirely distinct cha- 
racter of the cells of the end-sac as compared with those of 
the kidney counts for little ; my description of the differences 
of the kidney and duct-cells and their abrupt distinctness (no 
transitional kinds of cell existing) in the gland of Squilla 
7uight equally well be employed to suggest that the kidney 
and duct regions are of separate origin. In view, then, of the 
scanty and conflicting evidence on the subject, we are not in 
a position to draw conclusions respecting the ectodermal or 
mesodermal origin of the end-sac, still less to discuss the 
homologies either of the various parts of the antennal and 
maxillary glands or of the glands as a whole. Future inquiry 
can alone decide whether or not these Crustacean leg-glands 
(rudiments of which, it must be remembered, have been found 
in connection with the maxillipedes [15] and other thoracic 
limbs in addition to the second antenna and second maxilla) 
are to be compared with the ectodermal crural glands rather 
than with the mesodermal excretory organs of Peripatus as 
heretofore. 
