Dec. ii, 1879] 



NA TURE 



M5 



supported by certain experiments, is as follows : — Fa 

 into the liver is there changed into materials fitted for the blood, 

 the albumenoids into nitrogenous and saccharine substances, the 

 amyloiils into glycogen or " liver sugar." In preparing sugar for 

 the blood, the liver exercises its chief function by supplying easily 

 combustible fuel. The combustion of this fuel takes place in the 

 capillaries, whither oxygen is also carried by the blood. With 

 regard to the place of combustion being in the capillaries, in 

 contact with tissue, there is no longer a question ; the novelty 

 claimed by Dr. Le Conte is in respect to the preparation by the 

 liver of the fuel for this combustion. He does not concede that 

 the tissues are themselves burned in the process. He regards 

 the liver as a sort of storehouse, and asserts that the fuel it 

 provides one day may not be consumed till the next day in the 

 capillaries. Many arguments were brought to bear in support of 

 these views. The paper elicited a brilliant discussion in the 

 meeting, for although the main point, the alleged function of the 

 liver, was cheerfully conceded, a question was raised as to the 

 use of the word "combustion " in describing vital processes; 

 such use of the term being ably opposed by Dr. J. Lawrence 

 Smith, who regards oxygen as serving an alimentary rather than 

 a destructive purpose in the animal economy, while Dr. G. F. 

 Barker argued that a true combustion was performed where the 

 oxygen united with carbo-hydrates and the process was accom- 

 panied by evolution of heat. 



A paper delivered by Dr. George F. Barker had for its title 

 " On Arago's Experiment.'' It bore reference to the theory 

 which asserts that a wire becomes a magnet during the passage of 

 electricity. This was called in question about fifteen years ago 

 by Prof. Franklin Bache, of Philadelphia (brother of the late 

 Alexander Dallas Bache of the U.S. Coast Survey). He found 

 that when the magnetic field was cut in two by means of a disk of 

 cardboard, a wire that had previously supported a quantity of 

 iron filings, suddenly dropped them. He inferred that the 

 support of the filings had not been due to the wire being a 

 magnet during the passage of the current, since the current was 

 still passing when they dropped. Their previous support, before 

 the interference of the cardboard, was therefore to be attributed 

 either to their magnetic adhesion to one another, or to the direct 

 influence of currents circulating in the magnetic field which were 

 cut in twain by the cardboard. Dr. Barker has been experi- 

 menting with a very powerful magneto-electric machine of the 

 Wallace pattern. It was capable of heating a quarter of an inch 

 gas pipe, three feet long, to bright cherry redness in a minute. Its 

 current was used with a copper wire in Dr. Barker's experiments : 

 the question at issue being whether this copper wire became a 

 magnet during the passage through il of the electric current. A 

 five inch iron spike was held under and close to the wire ; the 

 gravity of the spike was lessened, but not sufficiently to support 

 it, even when it was brought within the 1000th of an inch of the 

 wire. But as soon as the spike actually touched the wire, it 

 stuck fast, was wholly supported, and arranged itself transversely 

 to the wire. When the spike was withdrawn from the wire by 

 only the 1000th of an inch, it fell, being no longer sufficiently 

 attracted. Dr. Barker regards this as showing that the attrac- 

 tion in the wire is greater than that in the field. The wire was 

 then pas-ed perpendicularly through a hole in a glass plate on 

 whose upper surface iron filings were sprinkled ; these, when 

 the current was passed through the wire, arranged themselves on 

 the plate in concentric circles around the wire, thus indicating 

 that such was the direction of the currents in the magnetic field. 

 When the spike was placed near the wire and parallel to it, but 

 suspended by the upper end, the lower end moved in the direc- 

 tion of the field-currents, throwing the spike out of perpen- 

 dicular. These observations were regarded by Dr. Barker as 

 evidence that the wire becomes a magnet in the experiment of 

 Arago. 



Prof. J. S. Newberry delivered a paper on the vegetation of 

 the Atlantic cat of North America in the cretaceous period. 

 He began by briefly sketching the position of the cretaceous in 

 the United States (and specially the lower cretaceous), along the 

 eastern base of the Appalachian chain. A large collection of 

 fossil leaves from this horizon, obtained in the green sands of 

 New Jersey, was exhibited ; it included many leaves from trees 

 of the salix family, in great variety ; and leaves and twigs of 

 conifers ; the specimens were of remarkable beauty and 

 clearness of detail. These fossils indicate that the dawn of the 

 cretaceous period in this country was attended by a temperate 

 climate. It seems probable that the plants of that periud spread 

 from America to Europe before the tertiary age, and were 



destroyed by the glacial epoch, after which, an Asiatic flora, 

 spreading westward, filled the void. In a discussion upon this 

 paper, Prof. Marsh stated his belief that these fossil leaves were 

 older than the lowest cretaceous marls of New Jersey, in which 

 we find crocodilian and other remains indicative of a warm 

 climate. A similar question had arisen abouc fossils from 

 Dakotah ; animal remains at first regarded as cretaceous, but 

 now known to be Jurassic. Local proximity of formations 

 differing widely in age, is not uncommon at the West. Within 

 fifteen or twenty feet of a place where he picked out remains of 

 dinosaurs, crocodiles and the like, he had found at fifty feet lower 

 depth, the ichthyosaurus. Dr. Newberry said that the clays 

 referred to in New Jersey undcrrun the marl beds, and are a 

 shore deposit, probably a freshwater one. Prof. Mar-h ho| ed 

 that these localities would be very thoroughly explored. Up to 

 the present date we know of no cretaceous mammal ; this is the 

 most serious break in our paloeontological record. Prof. Rogers 

 mentioned that certain fossils obtained in Virginia sandstones 

 had been classed as Wealden, but he was inclined to consider 

 them as on the border line between cretaceous and Jura-sic. 

 He regarded the position of the New Jersey fossils as yet open 

 to question. Prof. Newberry sketched on the blackboard a 

 sectional view of the strata in the New Jersey locality. Prof. 

 Marsh suggested that these conifers and willows may have grown in 

 elevated positions, on mountain sides, where they would have a 

 temperate climate though it was tropical at the base of the moun- 

 tains ; and that these forests might have been dislodged by flood 

 or avalanche, and carried down into the swamps at the base. It 

 was long supposed in Europe that there was no angiospermic 

 flora below the miocene, and when Prof. Marsh picked up 

 there the leaves of an angiosperm in the cretaceous, the speci- 

 men was regarded as a great curiosity. In this country such 

 fossils were abundant ; but as to the Jurassic flora we know too 

 little to speak with any certainty. Prof. Rogers staled that an 

 investigation of Virginia and Maryland clays, now in progress, 

 would probably solve this question ; and Prof. Newberry 

 expressed a similar hope in regard to certain researches on the 

 shores of Buzzard's Bay, Mass. 



A second paper by Prof. Newberry was descriptive of some 

 interesting deposits of gold and silver ores in Utah and Colorado. 

 Specimens were shown of sulphate of baryta with ruby silver. 

 The Horn silver mine of Utah had $20,000,000 of ore in sight ; 

 the footw all was limestone ; the sandstones are full of the impres- 

 sions of plants, the plants themselves being replaced by horn 

 silver. Such impregnation by a metal is rare, but there are 

 parallel instances with copper, in New Jersey, in porous sand- 

 stone. Near the Horn silver mine is one of a conglomerate rock 

 containing a rich argentiferous galena, going down at least 200 

 feet, and yielding §50 to S60 to the ton. A similar class of 

 deposits has been found in Colorado, in the district of the Silver 

 Cliff mine, a region of trachytic rock like that of the Horn silver 

 district. It v. oulcl appear that when the trachyte had been heated 

 so as to be softened, while in the shape of balls of various sizes, 

 the ores had coated them and filled their crevices. The ground 

 is covered with this rusty-looking rubbish. At depths of 150 

 feet in it, silicified wood is sometimes found, and occasionally 

 free gold, or " wire " gold. A man named Bassick, a sailor who 

 had been round the world, and was quite penniless, picked up one 

 of the rusty trachyte lumps and succeeded in having it assayed ; 

 the yield was §50 to the ton. He was thus led to the discovery 

 of what i- n iw known as the Bassick mine, which he eventually 

 sold for Si, 000, 000. Silver Cliff is distant about six miles ; it is a 

 hill of shattered rock — breccia which has been cemented together ; 

 the mining operations there have gone 250 feet below the surface, 

 into a zone of oxidized ore ; the rock of the hill itself is worth 

 §50 to .?6o per ton, and its quantity is simply enormous. From 

 other mines specimens were exhibited containing large quantities 

 of arsenic, the ore being also accompanied by veins of orpiment 

 and realgar. Specimens from Leadville mines showed the ro- 

 gress of change from carbonate to galena ores. The limestone 

 surface had been eroded, and then porphyry was poured over it ; 

 the fissure veins were formed in this contact. The famous 

 Leadville deposits are not so rich as had been supposed ; s eci- 

 mens picked out for a-say were very choice ; in general the ore 

 contains iron and a great deal of silica. There are two gold 

 mines in Leadville, one of which is ferruginous quartz. The 

 town itself is vile. Its climate is repulsive. It is at an elevation 

 of 10,500 feet, and water is scarce, so that the whole place is 

 covered with at least 5 inches of dust. There is no sewerage, 

 and this dust is the filth of the town ; the air is full of it, and it 



