INSTRUCTIONS FOR COLLECTING AND FIXING ROTIFERS 



IN BULK.i 



By P. DE Beauchamp, 



Priparateur d, la Faculle des Sciences de Paris. 



A glance at the published zoological results of scientific expeditions 

 is sufficient to show that rotifers are conspicuous by their rarity, 

 if not by their total absence. This is accounted for by the smaU 

 interest generallj^ accorded these animals, as well as by the fact 

 that investigators, even when devoting their attention exclusively 

 to the fresh-water fauna, rarely procure material in such condition 

 as to be of any use for systematic work. Rotifers are very delicate 

 and contractile, and in collections preserved in bulk in alcohol or 

 formaUn they become as a rule unrecognizable, with the exception 

 of those species which have the body incased in a chitinous shell or 

 lorica; in some cases this is sufficient for specific determination. In 

 the case of the genera Anursea and BracTiionus this has become a 

 positive misfortune, as it has resulted in an absolutely unjustifiable 

 multiplication of species based on the excessively variable spiny pro- 

 longations of the lorica. 



It may be objected that this void is of small importance, as it is 

 generally conceded that rotifers are distributed with almost abso- 

 lute uniformity all over the world.^ But it is equally well known 

 that there is a host of rare and local forms, often of the greatest 

 interest to the morphologist, which can be discovered only b}' care- 

 ful exploration. As an example, it is sufficient to mention the famous 

 genus Trochosplisera, which although widely distributed appears to be 

 confmed to subtropical latitudes. Furthermore underlying this appa- 

 rent uniformity there is a multitude of problems relating to the means 

 whereby it is established and maintained, and they can be solved 

 only by an exact knowledge of the faunal development under varying 

 conditions and in different environments. As specially important 



> Translated and adapted from Archives de zoologie exp6rimentale et gfinfirale, ser. 4, vol. 4, 1906, 

 Notes et revue, pp. xxvii-xxxiii, by U. K. Harring, Bureau of Standards. 



* See on this subject: C. T. Hudson, Journ. Roy. Micr. Soc., 1S91, p. 0; V. G. Thorpe, Joum. Roy. 

 Micr. Soc., 19m, p. 485; H. S. Jennings, Bull. U. S. Fish Comni., vol. 19 (1S99), 1900, p. 07. 



Proceedings U. S. National Museum, Vol. 42— No. 1893. 



181 



