24 
PROGRESS OF MICROSCOPICAL SCIENCE. 
(a) The spindle-cells enlarge and contain several nuclei which can 
be identified, whilst within the cell, as being of a similar nature to 
red blood-corpuscles. A current of blood-plasma from the nearest 
vessels passes, at the same time, into the interfibrillary space in which 
the spindle-cells lie. 
(b) The nuclei escape from the spindle-cells into this space, where 
they are indistinguishable in appearance from the ordinary red blood- 
corpuscles. 
(c) By a process of diapedesis the formed elements of the nearest 
blood-vessels pass into this space and the circulation is established. 
Various appearances lead the author to suppose that the fibrine of 
the plasma solidifies on the outer surface of the current and forms the 
substratum of the new vessel, and on this substratum the white blood- 
corpuscles fix themselves and spread out as an epithelium. 
From interfibrillary spaces in the inflamed cornea, in wdiich forma- 
tion of blood-vessels -was actively taking place, the author has isolated 
white corpuscles in various transition stages towards the appearance 
and shape of epithelium ; and, from rapidly enlarging vessels, cells 
which, from their form, he believes to be transitionary to that of smooth 
muscular fibre. 
As the new capillary forms, the enlarged spindle-cells decrease 
to their ordinary size. 
In preparations of blood-serum of the frog sealed up, after a few 
days, the hfemoglobin may be observed to assume special forms inside 
the corpuscle, or to disappear from it, and so produce changes in the 
appearance of the corpuscle identical with those described by Arnold 
as taking place in the tongue of the living animal after diapedesis. 
The above observations were made chiefly on the cornea of the frog 
and rabbit ; and the inflammation was mostly produced by solid nitrate 
of silver, the passing of a thread, and the application of methylated 
alcohol. 
In the winter frog ( Bana esculenta), cauterized in the centre of the 
cornea, the first entry of white corpuscles attributable to inflammation 
was observed, after forty-eight hours, in the wider spaces near the 
limbus. After four days they could be observed in considerable 
numbers, and 2-6 could be seen in one so-called space (lacuna). 
The Heart of the Snail. — Dr. M. Foster and Mr. Dew-Smith, who 
have been conducting some interesting physiological experiments on 
the snail’s heart, give the following account of its structure.* 
While the auricle is a sac, with quite thin and smooth walls, the 
bundles of fibres in the ventricular walls bulge out largely into the 
cavity, and are so arranged that the ventricle has the same spongy 
structure as that of the frog and many other animals. Neither in the 
auricular nor ventricular wall can the presence of any nerve-cells, or 
collection of nerve-cells in the form of ganglia, be detected, whether 
in fresh specimens or in those treated with various reagents. The 
interlacing intricately-arranged bundles of fibres are composed of a 
granular protoplasmic-looking tissue, quite unlike the ordinary mus- 
* Vide ‘Proceedings of the Royal Society,’ No. 1G0. 
