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Final Notes on the So-Called Desiccation of Rotifers. 



By Henry Davis. 



(Read November 27th, 1885.) 



A writer in the " Monthly Microscopical Journal " for June, 

 1873, criticising, in a friendly spirit, a paper on Rotifers I had 

 recently read, intimated that its chief merit consisted in its 

 certainty of closing all contention, and in putting the " inevitable 

 dried Rotifer " at rest for ever. But he was mistaken ; the dry 

 Rotifer discussion, like the creatures themselves, may lie dormant 

 for a time, but being " scotched, not killed," it revives again on the 

 smallest provocation. In fact you may well consider it has been 

 revived too often, and be little inclined to listen to a repetition, 

 however brief, of a much more than thrice told tale ; but when I 

 state that my short paper is called "final notes," &c, you will, 

 perhaps, see that there is at least one thing attractive about it, and 

 may, therefore, forgive a last effort to simplify and solve a very old 

 and difficult problem. 



These notes form a sequel to a paper read before the Royal 

 Microscopical Society, in April, 1873.* Before that date the 

 matter stood thus : — nearly two centuries had elapsed since it had 

 been discovered that certain minute aquatic creatures — now called 

 Rotifera — could be kept in a dry shrivelled condition for a consider- 

 able time, and then become active on being supplied with water. 

 But it was much later that special experiments were made to test 

 the endurance of these Rotifers under extended drought and 

 extreme temperatures. Very conflicting were the various accounts 

 of the results, and in consequence two opposing parties were 

 formed, one believing that the creatures could be boiled and baked 

 to any extent, and air-pumped until they were dry through and 

 through, or " desiccated," all without affecting their vitality. In 

 fact, repeated thorough drying only tended to prolong their lives, as 

 it was said they could be kept dry for an "unlimited time," and then 



* " A New Callidina, with the Eesult of Experiments on the Desiccation 

 ofKotifers." 



Journ. Q. M. C, Series II., No. 14. t 



