. Bulletin der US-Landwirtschaft. Landwirtschaft Die Landwirtschaft. 3. - Die europäische Ratte Flea: Larve. (Im Original.) Stark vergrößert. Zusammen mit den günstigen Bedingungen in Bezug auf die Ratten und Flöhe in Seehäfen, erklärt die Tatsache, dass die Krankheit in der Regel zuerst bricht in solchen Orten. Die Pest, wenn sie einmal eingeführt, wird rasch von Ratte zu Ratte nach der Flöhe. Diese Verbreitung wird durch die Tatsache, dass die meisten der Flöhe die Ratten verlassen, da sie sterben und Dritte weitergegeben werden. Es ist diese Flöhe, die sich durch den Tod von der Pest betroffenen Hosts festlegen, die der Chief Bedrohung für den Menschen bilden.

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. Bulletin of the U.S. Department of Agriculture. Agriculture; Agriculture. 3.—The European rat flea : Larva. (Original.) Greatly enlarged. together with the favorable conditions as regards rats and fleas in seaports, accounts for the fact that the disease usually first breaks out in such places. The pestilence, when once introduced, is carried rapidly from rat to rat by the fleas. This spread is increased by the fact that most of the fleas leave the rats as they die and pass to others. It is these fleas, set free by the death of their plague-stricken hosts, which form the chief menace to man. The method by which fleas convey plague germs has received con- siderable attention, and various theo- ries have been ad- vanced from time to time in an effort to explain the mech- anism of transmis- sion. It appears that the two most important methods are by contamination of the skin of man or other host by excrement voided by the infected fleas while feeding and the subsequent rubbing or scratch- ing in of the germ-laden material and by the injection of the disease organism into the wound made by the flea at the time of feeding. Researches made by Mr. A. "Y. Bacot, of the Lister Insti- tute, have proven this last method to be an important one. He showed that the entrance to the stomach of some of the fleas becomes plugged by a growth of the plague germs. This ultimately prevents the passage of food backward into the stomach, but does not prevent the flea from sucking up small quantities of blood, some of which is forced back into the wound after becoming laden with the disease organism. Close trade communication be- tween the nations of the world gives increased channels for the dissemination of various pests and diseases as well as opportunities for the furtherance of knowledge and the exchange of trade commodities. The colonization of new lands in the Tropics, the opening of a great artery of trade intimately connecting many of our ports with the commerce of the wo

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• bookauth
• bookcentury1900
• bookdecade1910
• booksubjectagriculture