796 THE AMERICAN NATURALIST. (VOL XXXII. 
There are many interesting new facts in the portion of the paper 
devoted to a description of the organs arising from the different 
germ-layers. Carrière discovered a pair of minute evanescent append- 
ages on the first brain (protocerebral) segment, and another pair 
on the third brain (tritocerebral) segment. Biirger confirms the 
accounts of preceding writers who claim that the antennez arise 
from the second brain (deutocerebral) segment. ‘Three pairs of oral 
appendages and three pairs of thoracic appendages are formed as in 
other insects, the latter notwithstanding the fact that the bee has an 
apodal larva. The thoracic appendages, however, soon flatten out, 
and Biirger finds that their hypodermal cell-layer thickens and 
becomes the imaginal disks, which, in the larva, are the rudiments 
of the legs of the imaginal bee. This interesting observation should 
be brought to the notice of those investigators who regard the 
gonapophyses of insects as dyshomologous with ambulatory legs, for 
the reason that the gonapophyses develop from larval structures 
resembling imaginal disks (Heymons). Bürger claims that he was 
unable to find rudiments of abdominal appendages on more than the 
first to fourth segments. His figures 28 and 35, however, show them 
on all the abdominal segments as in many insects more primitive 
than the bee. The pairs on the eighth, ninth, and tenth segments 
are peculiarly distinct and are evidently the rudiments of the gona- 
pophyses (ovipositor). Biirger nowhere mentions these structures. 
Another valuable observation made by Biirger is the presence in 
the embryo of the imaginal disks of the wings. Weismann and 
Graber claimed to have found these in the embryos of the blowfly, 
but their accounts are far from being satisfactory. The wing-disks 
of the bee arise as a pair of hypodermal thickenings with subjacent 
accumulations of mesoderm cells lateral to the leg disks in the meso- 
and meta-thoracic segments. They are beautifully shown in Biirger’s 
Fig. 173. The labrum arises as a pair of discrete appendages in 
front of the stomodeum. These ultimately fuse in the middle 
line. 
The origin of the trachex, spinning glands, tentorium, and flexor 
mandibule are described in detail. The tentorium is formed from 
two pairs of ectodermal invaginations resembling tracheal pits in the 
mandibular and second maxillary segments. The flexores mandibu- 
larum arise from a similar pair of invaginations in the first maxillary 
segment. The spinning glands are derived from a pair of invagina- 
tions immediately behind the second maxillary segment. The Mal- 
pighian vessels arise, as Carrière has shown in an earlier paper, 
