24 



THE AMERICAN MONTHLY 



[February, 



If the preparations stained in 

 picro-carniine are mounted in gly- 

 cerine the latter should be acidihed, 

 as for Frey's carmine — glycerine 

 100 parts, acetic or formic acid 1 

 part. If the sections are to be 

 mounted in balsam or damar, they 

 should be carried directly from the 

 staining solution into 95 per cent, 

 to 100 per cent, alcohol, and soon 

 afterward cleared in oil of ^cloves. 

 In this way but very little of the 

 yellow color will be taken out by 

 the alcohol. 



Note. — There have been three 

 ways of preparing the picro-car- 

 mine described. 



1. That by Ranvier in his TraitS 

 Technique de Ilistologie, p. 100. 



2. That given by Ores well Baber 

 in the Qttarterly Journal of Micro- 

 scojncal Scieiice, 1874, p. 251. 

 In Mr, Baber's method the evapo- 

 ration is at the ordinary tempera- 

 ture, and there is no filtration after 

 partial evaporation. He gives the 

 following test for the solution : 

 " Place a drop of the solution on a 

 piece of white filter paper, and 

 allow it to dry, when, if the picro- 

 carmine be good, a yellow spot is 

 formed, surrounded by a distinct, 

 red ring. 



_ 3. That given by Rutherford 

 his Practical Histology, p. 173. 

 Equal parts of picric acid and car- 

 mine are mixed at a boiling tem- 

 perature, and evaporated fo dry- 

 ness without intermediate filtra- 

 tion. 



Cleaning Foraminifera. 



In regard to cleaning Foramini- 

 fera when mixed with sand, all the 

 authorities say that if the dry sand 

 and shells be thrown or sifted into 

 water, the sand will sink and the 

 shells, because they contain air, will 

 float. The very reverse of this is 

 nearer the truth. If dry sponge 



sand rich in Foraminifera be sifted 

 into water, nearly all the shells will 

 sink, and whatever floats will be 

 sand, spicules, and an occasional 

 foraminifer. Trial will prove this 

 to be so. 



To separate the shells from the 

 sand, sift all the material into water, 

 stir the floating film of sand until 

 all that will sink has done so ; a 

 slide dipped under what still floats 

 will show it to be all sand, often a 

 group of sand grains surrounding 

 and enclosing an air bubble. 



Take about a teaspoonful of the 

 wet sand, and put it in a shallow, 

 nearly flat-bottomed dish or saucer, 

 and put on water enough to cover 

 it to a depth of about a quarter of 

 an inch. Now by rotating the dish 

 with a circling movement the Fora- 

 minifera will work out of the sand 

 and gather on its surface, mostly at 

 the center, but by carefully inclining 

 the dish and i-egulating the speed 

 of the circling movement the mass 

 of shells can be worked to one side of 

 the heap of sand, and thence dipped 

 up with a ball-pipette almost entirely 

 clean and free from sand, but 

 usually mixed with sponge spicules, 

 which it is almost impossible wholly 

 to get rid of. A boiling in weak soda 

 solution will often improve the 

 shells. 



As little water as possible must 

 be used in washing, as too much 

 will stir the sand as well as the 

 shells, and but little sand must be 

 washed at one time. o. m. voece. 



— Since our last issue we have 

 received the July number of Dr. 

 Pelletan's Journal de Microgra- 

 phie, which we supposed had ceased 

 to exist. This fact will not inter- 

 fere with the publication of the Ca- 

 talogue of the Diatomacem which 

 we have announced. The American 

 edition is the only one which has 

 the sanction of the author. 



