360 The American Naturalist. [April, 
rian coast of Behring Straits. Notwithstanding a few flat celt-like 
specimens from Peru, perforated as if for hafting, binding the handles 
on grooves, seemed to be the universal American characteristic, as 
against which omnipresent fashion in the new world, we know that the 
Neolithic peoples in Europe hafted all their stone axes through holes. 
perforating the axe. Why the latter method (granted migration during 
or after Neolithic times) never reached America remains to be ex- 
plained —H. C. Mercer. - 
MICROSCOPY. 
A Method of Preparing Rotifers.'—According to N. de Zograf 
rotifers may be fixed and mounted in glycerin, balsam or dammar and 
still retain the appearance of life by a slight modification of the method 
attributed to M. Rousselet in Hennegrey’s and Lee’s “ Traité de micro- 
scopie technique.” 
The animals in a watch glass are narcotized with a solution of 
cocaine, as used by Rousselet, except that the methylic alcohol is omitted. 
The solution is added drop by drop to the very small amount of water 
containing the rotifers. As soon as the movements of the animals cease 
without having contracted their cilliary apparatus, a considerable 
quantity of a 1 per cent. solution of osmic acid, diluted with 4-5 volumes 
of water, is turned upon them and allowed to act for about 2—4 minutes. 
Meanwhile a large amount of the liquid is removed with a pipette 
without disturbing the animals, which have settled to the bottom of the 
glass. Finally, a weak solution (about 1 volume to 8-10 of distilled 
water) of crude pyroligneus acid is poured over the animals, and per- 
mitted to act for from 5-10 minutes, after which the animals are 
washed two or three times with distilled water and then the water con- 
taining them very gradually replaced by alcohol, commencing with 50 
per cent. and finishing with absolute alcohol. 
Thus prepared the animals are found to have contracted neither 
their abdominal appendages, their feet, their band of cillia, nor their 
tentacles, and can be mounted equally well in glycerin, balsam or dam- 
mar. The protoplasm as a result of the action of the osmic acid has a 
faint gray or brownish tint; and structural details are plainly visible. 
The Scirtopods (Pedalion mirum) and the Rhizotes (Melicerta, Laci- 
nularia, Floscularia, Stephanoceros) give the most beautiful results, and 
‘Nicolas de Zograf. Sur une méthode de préparation des Rotateurs. Comp. 
Rend. Acad., Paris, CX XIV, 245-6. 
