794 MICROSCOPIC FORMS OF ANIMAL LIFE 



left much [longer in this fluid the animals will become more or less 

 blackened, and it is therefore necessary to remove the Eotifers as soon as 

 possible, by means of the fine pipette, in three or four changes of clean 

 water, so as to get rid of every trace of the acid. Finally the animals 

 are transferred into the preservative fluid, which is a solution of 2^ per cent. 

 formaldehyde (the commercial formalin is a 40 per cent, solution of 

 formaldehyde) . 



In this preservative the Rotifers are mounted in ringed or excavated 

 cells on micro-slides in the usual way. 1 



1 More detailed particulars in the treatment of the various species and in 

 mounting in cells will be found in Mr. Rousselet's papers on the subject, particularly 

 those of March 1895 and November 1898, in the Joarn. of the (Jiickett Mici: Club, 

 vol. vi. pp. 5-18, and vol. vii. pp. 93-97. 



