has given a list of 165 cases of traumatic epilepsy, 64 per cent of which were cured by trephining. Before Dr. Ferrier's experiments this trephining would have had to be done blindly. The knowledge gained by Dr. Ferrier's researches has also been useful in guiding to the spot where pus has accumulated in case of abscesses in the brain, and in indicating the site of tumors. Considering how recently these discoveries have been made, it in fact seems extraordinary that they should have been already productive of so much benefit. The operations on the animals are not painful after the exposure of the brain has been accomplished, and that is done under anæsthetics, nor does any pain follow the recovery from anaesthetic influence. The effects of the after-stimulations are simply the excitement of the wonder and curiosity of the animals at their involuntary motions. Probably a single sportsman inflicts more pain in a day's shooting than Dr. Ferrier has done in the whole course of his researches.
A New Natural Hydrocarbon.—Professor Henry Carvill Lewis has published a description of a new substance resembling dopplerite which has been found in a peat-bog at Scranton, Pennsylvania. It is black, jelly-like in consistency, and elastic to the touch when first taken from the ground, breaking with a conchoidal fracture, but becomes tougher and more elastic, like India-rubber, immediately on exposure to the air. Occasional seeds, having the characters of the spores of one of the higher cryptogams, occur in the substance, as well as in the surrounding peaty matter. The composition of the substance nearly corresponds with the formula C10H22O16, differing from that of dopplerite in the presence of much larger proportions of hydrogen and oxygen. Professor Lewis suggests that this product is, perhaps, an intermediate product between peat and coal, and proposes to combine it with dopplerite under the generic name of phytocollite ("plant-jelly").
Parasites.—Professor Arnold Heller, of Kiel, has recently published an interesting work on parasites, with particular reference to their import to men. It is only lately that the true origin and character of parasites have been at all adequately understood. Not very long ago they were supposed to be formed out of the substances of the body; and in the condition of knowledge at the time it was hard to account otherwise for their presence in certain parts of the system. They have also been supposed to be received by inheritance; and it has not been fully proved that, in rare instances, this may not be the case. It has, however, been shown that, as a rule, they are introduced into the system, either directly or through germs taken in with the food, breathed in the air, brought by unclean hands or with unclean dishes, or blown in with the dust. They are generally dependent on moisture for their vitality, and, finding in the bodily juices a favorable environment, may become suddenly active after having been long dormant in uncongenial situations. Most, if not all of them, probably existed originally in a free state, and have become wonted to what is now an exclusive abode by gradual adaptation in long time; in such cases, they seem to have lost some of the organs, such as those of locomotion, which they originally possessed, but which have become of no further use to them. Some of them have been made useful to man. The leech serves a valuable purpose in the healing art; the cochineal aphis furnishes a valuable dye; the tape-worm of the snipe tickles the palate of the hunter and the epicure as "maccaroni-piatti"—flat maccaroni; and the worms of fresh-water fishes are esteemed as food in some parts of Italy. The ichneumon flies and their tribe are of inestimable benefit in destroying the insect enemies to vegetation; and helpful moths have been discovered which prey upon the moths and other insects in the furs of rodents and the feathers of birds. Among vegetable parasites, ergot is valuable in medicine, and the mistletoe-berry is used in making bird-lime and fly-paste. It has been suggested that even intestinal worms may be good for children by helping to consume the excess of slime; and Jordan, of Mayence, has set forth that the animals that infest the skin of man may be beneficial by forcing him to look after the cleanliness of his person and clothing, and his intestinal worms by making him careful of his food. This view can not, however, be justified, even when we ad-
