Page:Popular Science Monthly Volume 53.djvu/447

Rh Worms that can hardly be classified, and larvae which give no clew to their parentage, exhibit beyond other animals the tendency to multiply rapidly, and to break away from one another at an early stage—a tendency which is so strong in the microscopic protozoa as to enter into the definition of the group. Fission, budding, alternation of generations, and spore formation are ultimately due to the same tendency. Weak animals make up, by their invisibility and their ability to scatter and evade, for the lack of powers to resist. If one polyp of a hydrozoa colony is bitten off, others remain, so that no enemy can possibly devour all the medusæ liberated from one colony or all the planulæ liberated from one medusa. Some animals and plants multiply by being torn to pieces or chopped small. Small animals are usually short-lived; and those that last as long as a year are often driven, like annual plants, to adapt every detail of their existence to the changing seasons. The naturalist who explores the surface waters of the sea soon learns that the time of year determines the presence or absence of particular larvæ.

importance and great expense of securing a pure water supply in large cities, and the carelessness with which the average householder handles his taps, have led many municipalities to consider the use of water meters. Such an attempt is now being made in Philadelphia, and is, it is stated, causing some dissatisfaction. There is no question that the water meter is a thing of the near future. The great care and expensive mechanism which are now coming to be considered necessary in securing a safe city water supply have added so much to its cost that wanton waste of it can not be tolerated; and, besides this, the small individual savings at each house, when added together in a large city, will go far toward furnishing a supply for various public sanitary purposes, such as daily flushing of the pavements, etc., and in this way also tend to improve the hygiene of the town.

halibut fishery on the northwest coast of the United States has developed into an industry of considerable importance, and there are now, Mr. A. R. Alexander says, in a Bulletin of the Fish Commission, nearly double the number of vessels engaged in it that there were four years ago. The demand for this fish five years ago was mostly limited to local orders; now large shipments are made to all parts of the West, and important consignments have been sent to the Atlantic coast by Canadian fishermen. The American catch finds a market in the States west of the Mississippi River. When this fishery began on the Pacific coast Port Townsend was its center, but for the last few years Tacoma and Seattle have absorbed the business. Halibut on the northern coast banks are very erratic. In places where they are numerous one day, few will be found the next. It frequently happens that a vessel will have good success for several days, and in a few hours' time fish will become so scarce that it is useless to remain longer on the ground. Fishermen can give no cause for this sudden disappearance other than that the halibut are traveling in schools, going from one bank to another, and not stopping long at any one place. Halibut do not seem to be very particular as to their food.

is stated in Industry and Iron that, after a series of tests which have proved satisfactory in every respect, the Prussian Railway Department has decided to introduce a mixture of acetylene and oil gas for train lighting on the state railways. It is said that by the admixture of one part of acetylene to three parts of oil gas the illuminating power of the latter is increased three hundred per cent. A flame consuming twenty-seven litres of the mixture per hour produces sixteen-candle power. The use of this mixture offers the great advantage that neither in manufacturing methods nor in the present oil-gas appliances in the carriages is any change necessary. As a pattern for the installation of the other gas plants to be erected on all the railway lines of the kingdom, the minister recommends the acetylene gas plant at Grünewald station, near Berlin. The present annual consumption of Pintsch oil gas on the Prussian railways is one hundred and twenty-seven million cubic feet.

curious formations known as bezoars, of common occurrence in the stomach and intestines of ruminants, are simply masses of indigestible material which, either owing to excessive size or other cause, are not