198 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE, 
3. All excretory ducts are devoid of smooth muscular 
fibres, and are invested with a cuboid epithelium of several 
strata, the innermost of which has a distinct cuticle. 
As regards the glands of the axilla, the author arrived at 
the following results. 
1. There exists in the axilla two different kinds of glands 
(axillary glands and sweat-glands). 
2. The axillary glands are very large, and show a very 
strongly developed muscularity. 
3. The epithelium of the axillary glands consists of one 
layer, is cuboid, shows a very broad cuticle, and is coloured 
brown by osmic acid. 
4, The excretory ducts of the axillary glands have an 
epithelium of sometimes one or more layers, but the inner- 
most stratum always possesses a cuticle. In the first case 
they sometimes possess muscles and are very wide ; in the 
second case they are mostly narrow and without muscles.— 
London Medical Record. 
2. Dental System of the Amphibia.—We can only mention 
Hertwig’s very elaborate memoir on this subject (‘ Archiv 
fiir Mikr. Anat.,’ vol. xi, supplement, pp. 208, five plates), in 
which he discusses the histology and development of the teeth, 
and the skeleton of the mouth in relation to embryology 
and finally in its bearings on the theory of the vertebrate 
skull. With reference to the latter point, Hertwig agrees 
with Huxley in his rejection of the old vertebral theory, but 
believes the true solution to be that of Gegenbaur, as given 
in his memoir on the Selachian fishes, and thus formulates 
his own views. The skull of vertebrates originates from the 
most anterior division of the axial skeleton by fusion of a 
large number of metamera, at a time when the axial skeleton 
shows no ossification. The inferior arches pertaining to the 
individual metamera form the visceral skeleton. In the Sela- 
chii we have the immature developmental stage of the skull, 
which is only transitory in the higher animals, viz., a com- 
plete cartilaginous capsule, which is the primordial crani- 
um. In Ganoid and Telcostean fishes, in Dipneusta 
(Lepidosiren, Ceratodus) Amphibia, and in all amniotic 
vertebrates, the skull is variously altered by ossification. 
The cranial bones originate in two ways. A certain portion 
of them are derived from the dermal skeleton, that is, from 
structures which, in the progenitors of these vertebrate classes 
named above, formed a continuous investment of scales 
or plates over the whole surface. By various processes 
these become changed into bony plates, and some of 
them becoming more deeply situated, become attached to 
