ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
49 
the pars intermedia of the hypophysis secretes a substance which has a 
profound effect on the melanophores. The absence of the hormone results 
in permanent contraction of many of these cells, and expansion of the 
xantholeucophores. Its presence in large quantities, such as follows the 
transplantation of the glandular tissue, causes maximum expansion of 
the epidermal and corial pigment-cells and contraction of the bearers of 
guanin and xanthin. The hormone of the pars intermedia of the 
hypophysis is an internal regulating agent of high potency, the effects 
of which are continuous, and not to any extent influenced by changes 
in the environment. It is probable that in the experiments the hormone 
acts directly upon the melanophores themselves by way of the blood 
stream, and not through the intermediation of the nervous system. 
But the second possibility is not rnled out. J. A. T. 
&. Histolog-y. 
Development of Hepatic Cell in Hedgehog. — P. Roberto Chaves 
( ComrpUs Rendus Soc. Biol., 1920, 83 , 879-81). There is a series of 
ontogenetic transformations in the hepatic cell. During embryonic life 
the cell becomes vacuolated, increases in volume, and becomes loaded 
with fat which disappears in the later phases. The chondriosomes, at 
first very small, are transformed into rodlets and larger granulations. 
The vacuoles flow together and increase in size, forming a secretory 
product which is probably expelled when the digestive processes begin. 
It disappears in the sucking mammal. After birth the transformations 
continue, and those of the chondriosomes are remarkable. The fat 
reappears in connexion with lactation. J. A. T. 
Paranucleus of Pancreatic Cell. — P. Roberto Chaves ( Comptes 
Rendus Soc. Biol., 1920, 83 , 881-4). Some paranuclei are artefacts, 
but others are real. In the pancreatic cells of the hedgehog there is a 
migration of nucleoli from the nucleus. In the cytoplasm they begin 
to exfoliate, forming one or two or many enveloping lamellas. They 
seem eventually to dissolve in the cytoplasm. J. A. T. 
Structure of Fused Bones of Frog. — Sunder Lal Hora ( Records 
Indian Museum , 1920, 19 , 188-4). In the tibio-fibula of Rana tigrina 
the bony substance in the middle where the two bones are fused shows 
a regular system of canals instead of the usual compact structure of 
superimposed thin lamellse. Seen under the microscope, this canalicular 
system appears identical with the Haversian canal system in the bones 
of higher Vertebrates. Sections of other fusions, e.g. between the radius 
and ulna, showed a similar system of canals. J. A. T. 
c. General. 
Blood Vascular System of Sphenodon. — Chas. H. O’Donoghue 
[Phil. Trans. Roy. Soc. London, 1920, 210 , 175-252, 3 pis.). The 
heart is on the whole reptilian, but of a simple unspecialized type, in 
which the three main arterial vessels, instead of opening directly from 
the ventricle, come off by a short common trunk, possibly a remains of 
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