208 Transactions of the 



spondent, who made his statement quite unexpectedly and without 

 a question being put. " They are very slimy, and when first 

 getting out are much hampered by the stuff sticking to them." 

 But admitting the gelatinous varnish over a naturally dried rotifer, 

 would such a coating be sufficient protection against the searching 

 absorption of sulphuric acid in vacuo ? Yes : I produce some 

 grapes which are coated with gelatine ; they have been with sul- 

 phuric acid in the exhausted receiver for seven days and nights. 

 On breaking the protecting envelope they are found fresh and 

 juicy ; far more so than some from the same bunch which, put by 

 in a cupboard, are now shrivelled and mouldy. 



We can now see how it is that isolated rotifers put singly, or in 

 small numbers, on a glass slip, and with thin cover, and allowed to 

 dry, very seldom recover when moistened ; for in crawling excitedly 

 over the slide, as they generally do, trying to find more water or 

 protection in their usual refuge — sand and dirt, they part with much 

 of their adhesive covering, the evaporation of the small quantity of 

 water is so rapid that they have no time to settle down quietly as 

 usual while more coating is secreted ; they roam about almost to the 

 last minute, when they are overtaken by the drought, shrink hastily 

 into a ball to dry and to perish. 



Having shown that the creatures need not of necessity be really 

 dry, however we may endeavour to dry them by moderate con- 

 tinuous heat, or by the so-called complete desiccation of the air- 

 pump, it only remains to demonstrate the fact that they are not dry. 

 A dry trough rich in philodines was kept in the vacuum for three 

 days with acid, then removed, and at once transferred to a long dry 

 test-tube, and the closed end immersed in boiling water for two 

 hours ; then with a pencil and the aid of a hand-magnifier, the 

 pink contracted bodies were picked out, put on a ledged glass slip, 

 and covered with a thin circle. They were then examined under a 

 quarter-inch, and seen to be highly refractive, and like rubies ; with 

 increasing pressure the tough yielding balls at last burst, and after a 

 few minutes, and repeated squeezings, emitted two distinct fluids, 

 one watery, which diffused through the broken mass, and another 

 oily — a yellow-pink fluid in minute smears — changing to drops 

 when water was run under the cover. In another case oil was 

 applied to the edge of the cover, run in, and the yellow fluid was at 

 once dissolved. 



From these experiments, and from other considerations, it seems 

 only reasonable to conclude that these rotifers become torpid in 

 drying externally ; that their vitality, though intact, is maintained 

 only by the slow consumption of their bodies. It is true they are 

 in air-tight cases ; but experiment shows that they can, even when 

 most active, bear the absence of air with impunity for a consider- 

 able time. I have had them in water in the exhausted receiver of 



