756 MICROSCOPY. 
Aw Error Correctep.— During the past summer and autumn 
many western and perhaps some eastern papers contained accounts 
of the discovery of a human skull in the carboniferous limestone 
of southern Kansas, by one of the instructors at the Catholic 
Osage Mission in that state. Its determination as a cranium re- 
posed on the authority of a physician of the town. Deeming the 
statement to be incredible, some later newspaper article asserted 
the specimen to be the skull of a deer. As this determination is 
not more reasonable than the first, I requested some photographs, 
which were obligingly sent by mail. These representing an object 
very much like a human cranium, I determined to visit the Mission. 
On reaching it I was kindly shown the specimen by Father Schu- 
macher, the principal. It proved to be the broad body-whorl of a 
large cephalopod shell, allied to Goniatites. Some specimens ex- 
hibited with it as petrified portions of a hay-stack which had been 
long exposed, were fragments of some kind of slag.—E. D. Core. 
MICROSCOPY. 
Exupations or DIPATHERIA AND Croup. — Dr. Jabez Hogg, 
President of the (London) Medical Microscopical Society, in a 
recent communication to that society, combats the somewhat 
prevalent doctrine that diphtheria and croup are essentially the 
same disease. From the bold assertion that nothing but a “ clin- 
ical tradition” separates these two diseases, and from the contra- 
dictory evidence of clinical medicine, he turns to histological 
anatomy for a solution of the difficulty, and maintains that a sharp 
line can be drawn between the diphtheritic membrane and the 
croupous cast. The former he finds a dense, compact, opaque, 
felt-like membrane, firmly adherent and not removable spontane- 
ously, which when forcibly detached comes away in fragments and 
leaves a broken and bleeding surface. This membrane, under & 
microscopical power of X 350, is seen to consist of fibrous and 
connective tissue, shrunken and compressed cells (epithelial, mus- 
cular, glandular, and even cartilaginous), fat molecules, muco-pu- 
rulent or glandular corpuscles, crystals, starch granules, fungus 
spores, and other foreign bodies. On the other hand the croupous 
cast is a delicate, semi-transparent, often gelatinous exudation, 
not so intimately connected with the subjacent mucous membrane 
but that it is easily separable as an imperfect cast which is often 
_ thrown off during a fit of coughing. Under the same maguif 
