The Rotifer, a singular creature, although it can only truly live in water, inhabits the moss on house-tops, dying each time the sun dries up its place of retreat, to revive as often as a shower of rain supplies it with the moisture essential to its existence; thus employing several years to exhaust the eighteen days of life which nature has allotted to it.  These creatures were discovered by LEUWENHOECK, and have become the types of a class already numerous, which undergo the same conditions of life, and possess the same faculty.  Besides the Rotifera, the Tardigrades, (which belong to the Acari,) and certain paste-eels, all exhibit a similar phenomenon.  But although these different species may die and be resuscitated several times in succession, this power has its limits, and each successive experiment generally proves fatal to one or more individuals.  SPALLANZANI, in his experiments on the Rotifera, did not find that any survived after the sixteenth alternation of desiccation and damping, but paste-eels bore seventeen of those vicissitudes.

SPALLANZANI, after thoroughly drying sand rich in Rotifera, kept it for more than three years, moistening portions taken from it every five or six months.  BAKER went further still in his experiments on paste-eels, for he kept the paste from which they had been taken, without moistening it in any way, for twenty-seven years, and at the end of that time the eels revived on being immersed in a drop of water. If they had exhausted their lives all at once and without these intermissions, these Rotifera and paste-eels would not have lived beyond sixteen or eighteen consecutive days.

To remove all doubt as to the complete desiccation of the animalcules experimented on by SPALLANZANI and BAKER, M. DOYERE has published, in the Annales des Sciences Naturales for 1842, the results of his own observation, in cases in which the mosses containing the insects were dried under the receiver of an air-pump and left there for a week; after which they were placed in a stove heated to 267 deg.  Fahr., and yet, when again immersed in water, a number of the Rotifera became as lively as ever.

Further particulars of these experiments will be found in the Appendix to the Rambles of a Naturalist, &c., by M. QUARTREFAGE.

INDEX.

* * * * *

ABOU-ZEYD, his account of fish on dry land, 350 n. 
Abyssinia, fishes of, 352.
Acalephae, 398. See Radiata. 
Acanthopterygii, 360. 
Accipitres, 245.
Acherontia Sathanas, 427
Adam’s Peak, elephants on the summit, 109. 
AElian’s account of the mermaid, 69.
his statement as to the export of elephants from Ceylon, 77 n., 209 n.
  error as to the shedding of the elephant’s tusks, 79 n.
  describes elephants killing criminals