32 
PROGRESS OF MICROSCOPICAL SCIENCE. 
animal remains. Ho thinks that certain of the projections upon them 
are the equivalents of the ncmatophores in living Hydroida. 
The Double Markings of Triceratium are the subject of a paper by 
Col. Dr. Woodward, in the ‘Lens’ [last number], and are illustrated 
by an admirable Woodbury Photo-relief print, which brings them out 
with the most marvellous distinctness. These photographs we wish 
we could reproduce, for they certainly most fully bear out the remarks 
made by Dr. Carpenter in his work on the microscope, when he says 
that “ in certain species of Triceratium, Coscinodiscus, and Actino- 
cyclus the floors of the hexagonal depressions are studded with mark- 
ings resembling those of Pleurosigma, and these are particularly con- 
spicuous in the beautiful Heliopelta.” Previous attention had been 
drawn to this circumstance by Stodder, Ralfs, and Reynolds. Dr. 
Woodward states that he has repeatedly verified the accuracy of the 
above statement for all the genera named, but limits himself in the 
present paper to a few remarks on a single species of Triceratium. 
Professor Christopher Johnston, of Baltimore, very kindly lent him, 
not long since, a slide containing a large frustule of Triceratium 
fimbriatum, on which the headings, which with high powers can be 
made out on all the species of Triceratium, were remarkably distinct, 
and hence capable of being shown with a comparatively moderate 
magnifying power. The author then describes the method of photo- 
graphing adopted by him for the two photos which appear in the 
illustration. He states that when the rows of dots seen in the 
picture of the broken frustule arc examined by immersion objectives 
of the highest power and the best quality, they appear with white 
light as round garnet-red beads on a greenish ground, approximating 
in size and appearance the beads of Pleurosigma angulatum. He has 
endeavoured to obtain photographs of them with high powers, and 
sent silver prints of the results to the editor and the society. The 
comparative thickness of the frustules, and the marginal walls of the 
areolfe, interfere considerably with clear definition, with these high 
powers ; still, he thinks an impartial examination of the photographs 
sent will dispel all doubts as to the real nature of these markings. 
A Skin Disease ( Molluscum contagiosum) resulting from a Parasite. 
— It is stated that Mr. Balmanno Squire thinks that he has disco- 
vered parasitic spores in the sebaceous matter which forms the pulp 
of the tumours in molluscum contagiosum. The spores, he thinks, 
are somewhat longer than those of the parasite of favus. Mr. Squire 
believes that the parasite causes, by the irritation it excites in the 
sebaceous glands, the increased secretion of sebaceous matter which 
characterizes this disease. 
The Microscope in Entomology. — According to Mr. S. H. Scudder, 
who writes in the ‘ Entomologist’s Monthly Magazine,’ the microscope 
may be of advantage in the study of caterpillars — of course with 
low powers. But with such assistance he says that the shape 
and sculpturing of the head, the form of certain segments, and espe- 
cially the precise number, location, and disposition of the spines, 
thorns, and hair-emitting warts of the body will be found to furnish 
