SUMMARY OF CURRENT RESEARCHES. 
289 
Upper jaw. 
Lower jaw. 
1 1 
7 yr., 10 m. 
7 yr., 4 m. 
I 2 
^ 55 9 ,, 
8 53 3 „ 
C 
11 5, 9 „ 
10 „ 9 „ 
10 „ 10 „ 
Pm 1 
10 „ 2 „ 
Pm 2 
11 ,5 3 „ 
12 „ 4 „ 
M 1 
7 53 5 „ 
7 „ 
M 2 
12 „ 10 „ 
12 „ 4 „ 
M 3 
24 „ 
24 „ 
He makes three interesting generalisations : — 
(1) In higher-class schools the children showed a more rapid 
acquisition of the second set than in the Yolkschulen. This is probably 
due to the difference of nutrition. 
(2) The canine of girls appears about three-quarters of a year sooner 
than that of boys (as among anthropoids), and the same is true of the 
second molar. It well known that girls have for a time a more rapid 
rate of growth than boys. 
(3) Townsfolk show in about 3 per cent, of cases a loss of the lateral 
upper incisor, but in country-folk the percentage is only • 5 per cent. 
The absence depends greatly on the form of the gum ; among the towns- 
folk of Freiburg the dolichocephalic or leptoprosopic type prevails, in 
the country the brachycephalic or channeprosopic type. The former 
is associated with a high narrow gum, the latter with a flat broadly 
arched gum (Kollmann). 
Development of Auditory Ossicles.* — Hr. M. Zondek has investi- 
gated this difficult problem in embryos of rabbit, ox, and man. He 
agrees with the majority that malleus and incus are derived from the 
first arch ; he finds that the stapes arises in continuity with the hyoid 
arch, but the lamina stapedialis in connection with the labyrinth wall. 
Before malleus and incus become cartilaginous they form a continuous 
mass of cells, but with the chondrification a joint is formed. The 
author has some interesting notes on the various histological stages 
through which the arches and their derivatives pass. 
Menstruation of Semnopithecus Entellus.t — Mr. W. Heape gives 
an account of the menstruation of this monkey, describing fully the 
histology of the uterus in its different stages. These stages are eight in 
number, and belong to four different periods. The first period is that 
of rest, and contains the first or resting stage. In the second period, 
which is that of growth, two stages are recognised ; in one there is 
a growth of stroma and an increase of the vessels. In the third period, 
or that of degeneration, there is a breaking down of vessels, the forma- 
tion of lacunas, the rupture of lacunae, and the formation of the menstrual 
clot. In the fourth period, or that of recuperation, there is a single 
recuperation stage. Mr. Heape thinks that the existence of these 
periods, although they cannot be quite sharply defined, is nevertheless 
very marked and real, and they indicate that a substantial periodic 
growth of the mucosa has arisen by degenerative changes, when a 
fertilised ovum is not present. 
* Arch. f. Mikr. Anat., xliv. (1895) pp. 499-509 (4 figs.), 
f Phil. Trans., clxxxv. B. (1894) pp. 411-71 (7 pis.). 
1895 
u 
