BOB-WHITE—BONE 47 
ORTOLAN. Its good qualities have been described at length by Alex- 
ander Wilson, Nuttall, and Audubon, to say nothing of more recent 
writers on North-American ornithology, and to those authors must 
reference be made for its description and an account of its habits. 
From the purely scientific point of view the form is one of consider- 
able interest, as it seems to connect the Hmberizide (BUNTING) 
with the Jcteridy (GRACKLE, ICTERUS); and, though generally con- 
sidered to belong to the latter, is rather a divergent member of 
that Family. It is a bird that performs vast migrations, breeding 
as high as lat. 54° N., and in winter visiting the Antilles and 
Central and South America as far as Paraguay. 
BOB-WHITE, a nickname of the Virginian QUAIL, Ortyx vir- 
ginianus, aptly bestowed from the call-note of the cock. 
BONE or osseous tissue consists of phosphate and carbonate of 
lime, salt, and a few other earthy substances. Hollow bones contain 
marrow, a fatty substance with delicate connective tissue, except 
where it has been driven out by the penetrating Arr-sacs. On 
the surface of a bone, covered by a fibrous membrane, the periosteum, 
there open small, often microscopic, holes, which as ‘“ Haversian 
Canals” are continued through the walls of the bone into larger spaces 
or cancelli, and ultimately into the marrow cavity. These render 
possible the entrance of blood-vessels, air-cells, and nerves. Bones 
which have their entire substance or diploe between the outer and 
the inner lamella filled with cavities and cancelli are called cancellated 
or spongy; this is especially the case in the bones of the head of 
Owls, and to an enormous extent in the “horn” of the Hornbills. 
The bony substance forms consecutive layers around the Haversian 
canals. The layers themselves contain numerous irregular lacune, 
formerly but wrongly called bone-corpuscles, from which radiate 
numerous extremely fine canaliculi ; these communicate with those 
of neighbouring lacune and with the Haversian canals, securing 
thus access of blood and lymph to any part of the bone. 
Bone is never directly formed out of the indifferent embryonic 
tissue, it always passes through a stage of connective tissue. If 
this tissue ossifies directly, it becomes a primary or membrane 
bone; if the tissue is cartilage and finally supplanted by bony 
tissue, the latter forms a secondary or cartilage bone. Most of the 
bones of a bird’s skeleton pass during their development through 
such a cartilaginous stage. Membrane bones are principally some 
of those forming the cranium, as the parietal, frontal, maxille, and 
vomer. Bones which are developed in tendons by direct ossification 
are termed sesamoid bones, as the brachial and the crural patella. 
Either kind of bone can ossify from various centres, but these 
“centres of ossification” do not necessarily indicate that the bone 
in question is composed of a number of originally separate bones, 
