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SUMMARY OF CURRENT RESEARCHES RELATING TO 
remains shut, none of the colouring matter passes below the outermost 
epithelial layer. In special cases, e.g. frogs in 5 per cent, salt solution 
or patients in mineral baths, water may diffuse outwards through the 
skin ; but this is abnormal. 
Structure and Development of Cartilage in Cyclostomes.* — Herr 
J. Schaffer begins by discussing the soft or “ blue ” cartilage as seen, 
for instance, in the branchial skeleton of Ammocoetes. Its ground- 
substance is a simple honeycomb or alveolar system separating the 
cells; and these component cells or chondroblasts are able not only 
to secrete cartilaginous substance around themselves, but also to assimi- 
late the adjacent tissue, and to modify it into chondrogenic substance. 
In Ammocoetes , the primary cement-substance and the capsular substance 
produced by the cells are quite indistinguishable. In the soft or grey 
cartilage of Myxine, however, the intercellular septa show, in some 
places at least, a distinction between the primary cement-substance and 
the secondarily deposited capsular substance. Schaffer places this kind 
of cartilage between the branchial and the cranial cartilage of the larval 
lamprey. 
In the hard or “ yellow ” cartilage of Myxine , Schaffer interprets the 
capsular substance which fills the alveoli of the cement-substance, as 
the analogue of a cell- chamber, since acid anilin stains demonstrate an 
internal well-defined zone, the capsule proper, and an external unstained 
layer. By regressive changes, however, the capsules may be changed 
into ground-substance. The variety of cartilage, even in the same 
animal, is probably due to the diverse development of the components, 
— primary cement-substance, capsule-proper, and cell-chamber. 
As to the development, the author emphasises the assimilatory 
function of the chondroblasts. In the metamorphosis of the lamprey, 
the new cartilage is not formed by direct change — metaplasis — of the 
larval tissue, but there is new formation or immigration of chondro- 
blasts which form the new cartilage. Schaffer compares his results in 
detail with those of Studnicka who has recently worked at the same 
subject. 
Nerve-Endings in Tactile Hairs of Mammals. f — Herr E. Botezat 
has studied the innervation of the tactile hairs in mouse, rat, cat, pig, 
and other forms, chiefly by means of the methylen-blue method. His 
most important new results are the following : — 
(1) The nerve-fibres of the deep plexus of the inner hair follicle 
penetrate the vitreous or homogeneous membrane (between the outer 
root-sheath and the internal follicle), and form tactile menisci internal 
to it. These menisci occur not only in the lower part of the root-sheath 
swelling, but also in the deeper parts of the root-sheath which reach 
down to the papilla and form no swelling. 
(2) The real endings of the sensory hair nerves are the terminal 
fibres into which the sensory menisci pass. These project into the 
interior of the root-sheath and end freely between its cells. 
(3) From the annular plexus (of epidermic and follicular nerves)* 
which occurs in several animals, processes of the axis-cylinders pene- 
trate the vitreous membrane and form free endings internal to it. 
* Arch. f. Mikr. Anat., 1. (1897) pp. 170-88. f Tom. cit., pp. 142-69 (2 pis.). 
