1887.] MICROSCOPICAL JOURNAL. 69 
which are produced pierce the tissues and become encysted in the muscles 
or other closed organs. It appears that the Ol/ulanus tricuspis, a nematode 
of the cat, presents the same phenomena. This is an ally of trichina, which 
lives first in the muscles of the mouse, which serves it as a vehicle, then in 
the stomach of the cat, where it becomes sexual and complete. 
Infected muscle in the early state is hardly distinguishable from healthy 
muscle by naked-eye observation, but in the advanced stages of the disease 
the capsules are invaded with calcareous deposits which render them visible 
as white or grayish specks scattered through the muscle. 
Dr. Leidy says that children seem to suffer less from trichinosis than adults, 
and the explanation given is that from the ready production of diarrhoea in 
children the ova are expelled from the intestine before having time to perfo- 
rate its walls. 
The muscles nearest the intestinal lining, as ‘the diaphragm and the ab- 
dominal walls, are most infected by the parasite. 
The symptoms produced are at first of a dyspeptic character, followed by 
violent symptoms of gastro-intestinal irritation, often resembling those of 
Asiatic cholera. The muscles become hard and swollen and highly painful 
in movement; breathing may be performed only with difficulty, owing to 
invasion of the diaphragm. Fever is usually absent in mild cases, but exists 
in severe cases and of every grade, resembling typhus fever. 
The prognosis is very bad in severe cases, as no antidote to the parasite is 
known. 
In mild cases the best treatment is frequent purging by castor oil and tur- 
pentine and keeping up the powers of the system by diet. 
Dr. Leidy states that it was in a piece of boiled ham, from which he had 
partly made his dinner, that he first discovered ¢r7zchzva in the hog. 
Notes on diatom study.—II. 
By WM. A. TERRY. 
I have succeeded fairly well in cleaning diatoms by any of the published 
processes when the quantity operated upon was small; but, in attempting to 
clean a half pint of material or more at one operation, have frequently met 
with notable loss, sometimes amounting to the entire destruction of certain 
varieties. This I conclude to be partly due to the organic acids formed, as 
in certain experiments made for that purpose I have found that oxalic acid, 
and other compounds, formed by the action of mineral acids upon organic 
matter, were capable of dissolving the diatoms at a high temperature. ~The 
great volume of acid fumes given off in these processes is also very trouble- 
some. My process, detaited below, I consider an improvement, as it gives 
off no fumes of any consequence, requires no artificial heat, and is accom- 
plished in a few minutes, and, in many comparative trials, I have found a 
much larger proportion of the diatoms uninjured. On account of the varia- 
ble nature and amount of the organic refuse of different gatherings, accurate 
weights and measures cannot be given; but I will endeavor to make the gen- 
eral principles so plain that common ingenuity will suggest the necessary 
modifications. Suppose, then, that we have a recent fresh-water gathering 
that has not been dried. After washing out the coarser sand and straining 
out the coarse refuse, allow the material to settle in the vessel in which the 
operation is to be performed ; then pour off the water rather closely, so that 
the amount remaining shall be about equal in weight to the weight of the 
material dry. Then add finely pulverized bichromate potash in amount equal 
