AND DEVELOPMENT OF THE LIVER. 
135 
inch. It consists of an investing basement membrane, which is strongly 
marked; this supports a layer of pale granular matter, in which are im- 
bedded several small transparent cells : the cavity of the tube is wide, and 
is occupied by numerous very delicate transparent cells, in the interstices of 
which are dark clusters of biliary granules. At a, two of the transparent 
cells are shown which had escaped from the tube ; they are perfectly glo- 
bular and contain only a limpid fluid ; they are, I think, of constant occur- 
rence in the hepatic tubes of insects. 
Fig. 13. View of parenchymatous portion of the Blowfly’s liver (or adipose tissue) in 
early stage of its formation. Several nucleated cells, diameter y^o^h of an 
inch, containing granular matter, are seen lying in a pale granular blastema, 
along with several large oil* globules ; a vesicle and tube are in process of 
formation from the blastema : these will include one or more nucleated cells. 
{a) is a nucleated cell from the blastema, diameter -^^Q-oth of an inch, probably 
an early condition of the larger cells ; {b) a fully-formed vesicle, diameter 
yy-and of an inch, containing yellowish granular matter, and a nucleated 
cell. 
Fig. 14. An elongated vesicle, -^th of an inch long, xTr^h of an inch wide at its 
middle, formed of an homogeneous membrane, enclosing dark oily con- 
tents ; it is traversed in its whole length by a minute tracheary tube, which 
having become very fine issues from it at its upper extremity. (From brown 
Moth.) 
PLATE X. 
Figs. 15, 16, 17 from liver of Tench ; they represent minute biliary ducts isolated 
from the parenchyma. (15) exhibits a delicate homogeneous tubular mem- 
brane, in the interior of which are several large delicate epithelial cells ; the 
last of these lay so close to the extremity of the specimen, that it could 
not be determined whether the homogeneous membrane formed an actual 
csecal termination; diameter -yoVoth of an inch. (16) exhibits at its lower 
part the tubular character ; towards its termination this is lost : it has the 
appearance of a tract of granular matter with even borders ; several nuclei 
can be discerned in it ; diameter of an inch. ( 17 ) is a duct, y^th of 
an inch diameter, consisting of nuclear granules and granular matter ; its 
extremity is quite even, though it is difficult to determine whether it is 
completely invested by homogeneous membrane. 
Fig. 18. A minute duct, probably terminal, from liver of Perch; its diameter is 
s o^o oth of an inch : it consists of distinct nuclei, set as it were in a faintly 
mottled basis-substance. 
Fig. 19. A group of peculiar cells from the parenchyma of liver of Mackerel ; their 
diameter varies from x^o“o to of an inch. They have a well-marked 
