Nature Volume 88

Nature Volume 88

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 edition. Excerpt: ...Gardens it has been observed to be 28 per cent., both of which figures are very much above that of human beings. Weissman has sought to establish a correlation between longevity and reproduction, but Dr. Mitchell refuses to accept his interpretation. He believes, not that longevity has become adapted to reproduction, but that the rate of reproduction has been adapted to average specific longevity. In any case, the deathrate amongst prolific wild animals maintaining a stationary population must be stupendous; for instance, if a mouse produces only two litters a year of six young in each, then if all survive to maturity there will be fourteen mice where before there were only two, and if the population is to remain stationary twelve must die, and these figures may be regarded as probably below the mark where food is abundant. The relative prolificacy of the rodents as compared with many of the carnivora which feed upon them does not come within the scope of Dr. Mitchell's paper, but it is a remarkable instance of the interrelation of the system of life upon our planet that those which are preyed upon should be on the whole more prolific than those which prey. Possibly the shortest-lived mammals are to be found amongst the shrews, of which a solitary individual is tabled in Dr. Mitchell's records as having survived captivity for one month. Shrews are extremely difficut to keep alive under artificial conditions, and evidence has lately been produced to suggest that, in the case of the two commoner British species, the 'average duration of life is only about a year, but, since shrews are amongst the most prolific of mammals, this short period is more than sufficient for the maintenance of their numbers. It appears that there is no rule which...show more

Product details

  • Paperback | 780 pages
  • 189 x 246 x 39mm | 1,365g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236872029
  • 9781236872029