798 THE AMERICAN NATURALIST. (VoL. XXXII. 
somites of the third, fourth, and fifth abdominal segments. These 
cells, which seem to be restricted to the dorsal wall of their respec- 
tive somites, subsequently collect about a common center to form on 
either side a small oval body, — the ovary or testis. The vasa defe- 
rentia and oviducts arise from the mesoderm. The former terminate 
in the tenth, the latter in the seventh abdominal segment, in both 
cases in terminal ampullz as described by Wheeler for Xiphidium. 
A thickening of the hypodermis over the terminal ampulla represents 
the rudiment of the ectodermal portions of the reproductive organs 
(ductus ejaculatorius and vagina). 
The embryonic envelopes of the Hymenoptera promise to yield 
interesting results when carefully investigated. In the Phytophaga 
the envelopes are complete and typical, as shown by Graber in 
Hylotoma berberidis. In the other Hymenoptera hitherto studied 
only one envelope, the amnion, is formed. Carrière shows that it 
arises in the wall-bee from the peripheral portion of the blastoderm 
and persists only a short time. The exact mode of its obliteration 
is not clearly figured or described. By the time of hatching it has 
almost completely disappeared. Bürger claims that embryos of 
Polistes gallica, at least in the later stages, agree with Chalicodoma 
in possessing only a single embryonic envelope, and that this also 
disappears before the hatching of the larva. 
WILLIAM MORTON WHEELER. 
Tumors and Germ-Layers. — Since tissue differentiation in organ- 
isms has come to occupy so large a place in the attention of biologists, 
the general subject of tumors has assumed a biological interest that | 
is but little less than its medical interest. 
A recent paper by Dr. D. Montgomery, with a note by Dr. L. F. 
Barker,! dealing with a case of teratoma, contains so much of interest 
that it deserves to be more widely known to biologists than it is 
likely to become through the pages of a medical journal, The tumor 
was taken from the peritoneal cavity of a girl twelve years old. It 
was of the solid variety, że., it was not a single large cyst, but was â 
mass of tissue with a great iiiter of small cysts scattered through- 
out its substance. Its weight was two pounds. It was situated on 
the right side of the abdomen, and was attached to the ascending 
1 A Teratoma of the Adamia! Cavity, by Dougless W. Montgomery, M.D., 
with a Note on Dr. D. W. Montgomery’s Case of Teratoma, by Lewellys F. 
Barker, M.D. The Journ. of MiA Neita, vol. iii (May, 1898), No- 3» 
PP- 259-292. 
