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which they appear capable of retaining after dissection; 
they appear less dense than the jaws, but more so than the 
membranous tissues of the gizzard, to which they are united. 
The central corrugations are always the largest. 
Professor Williamson also called attention to the fact, 
originally noticed by Leeuwenhok and afterwards confirmed 
by Spallanzani and others, of the possibility of reviving 
these animals after protracted desiccation. He exhibited 
some small glass tanks or Rotiferous aquaria, some of which 
had been prepared by Lord S. G. Osborne, which had been 
dried up again and again. One of these, in a dry state as 
it had been for five months, was moistened by the addition 
of a little water, and in five minutes the animals were in 
full activity, looking thin and hungry, but perfectly vigorous. 
The experiments of Lord S. G. Osborne confirm the state- 
ments of Spallanzani, that these Rotifers may be dried up for 
years without vitality being destroyed. Tanks for the 
preservation and examination of these objects are readily 
made by joining two ordinary microscopic glasses on three 
sides by means of electric cement, and then stocked by the 
introduction of a little Rotiferous dust. In such tanks they 
multiply rapidly, the occasional addition of a few drops of 
water to counteract evaporation being all that is needed 
for their preservation. The above communication was 
further illustrated by some beautiful models constructed by 
Lord S. G. Osborne, and kindly lent for the occasion. 
