[Note 90: This can of course only apply to tribes tolerably well known to Europeans, and more or less frequently coming in contact with them. Of tribes in their natural state we can have no accurate data, and but few passing notes even that are worthy of confidence. Generally I have found children to be numerous among tribes who have never had intercourse with Europeans' and it is a well known fact that the increase of numbers in aboriginal tribes is checked in proportion to the frequency, or the extent of their communication with Europeans. At Flinders island to which 210 Van Diemen's Land natives were removed from Van Diemen's Land in 1835, this is singularly exemplified. In 1842 Count Strzelecki says, page 353--"And while each family of the interior of New South Wales, uncontaminated by contact with the whites, swarms with children, those of Flinders island, had during eight years an accession of only fourteen in number."] Upon inquiry into the causes which tend to prevent population going on in an increasing ratio among the natives of Australia, the following appear to be the most prominent. First, polygamy, and the illicit and almost unlimited intercourse between the sexes, habits which are well known to check the progress of population, wherever they prevail. Secondly. Infanticide, which is very general, and practised to a great extent, especially among the younger and favourite women. Thirdly. Diseases, to which in a savage state young children are peculiarly liable, such as dysentry, cold, and their consequences, etc. [Note 91: Huic accedit, ex quo illis sunt immisti Europaei, lues venerea. Morbum infantibus matres afflant, et ingens multitudo quotannis inde perit.] Fourthly. Wars and quarrels, occurring sometimes from the most trivial circumstances, and often ending in deaths, or wounds that terminate in death. The diseases to which the natives are subject, are with the exception of those induced by artificial living, as gout, rheumatism, etc. very similar to those which afflict Europeans, the principal being the result of inflammation, acute, or chronic, arising from exposure to the cold, and which affects most generally the bronchiae, the lungs, and the pleura. Phthisis occasionally occurs, as does also erysipelas. Scrofula has been met with, but very rarely. A disease very similar to the small-pox, and leaving similar marks upon the face, appears formerly to have been very prevalent, but I have never met with an existing case, nor has Mr. Moorhouse ever fallen in with one. It is said to have come from the eastward originally, and very probably may have been derived in the first instance from Europeans, and the infection passed along from one tribe to another: it has not been experienced now for many years.