ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 705 



Berlin blue by simple insertion of the syringe ; if the animal is 

 moving actively the injection runs forward with difficulty and in any 

 case the neck and head require manipulating with the finger or a wet 

 brush, in order to drive the injection through the narrow portions of 

 the vessels which occur at the joints- 

 Staining and Preserving Tube-casts.* — To stain and preserve 

 tube-casts, A. T. Parker finds a logwood solution better than any 

 other, made by adding five grammes of the extract of logwood, and the 

 same quantity of alum, to 100 ccm. of water. The extract and alum 

 should be thoroughly triturated before the water is added, and the 

 whole then left until the extract is completely taken up by the water, 

 which requires several hours, and then filtered. The best course to 

 pursue in staining is to shake the bottle containing the urine, then 

 pour it into a conical flask ; after several hours, when the deposit is 

 complete, either draw or pour off the supernatant fluid, and add 

 to the deposit about an equal quantity of the staining fluid. At 

 the end of one or two days, the casts will be stained a beautiful 

 reddish-purple. 



Casts prepared in this manner over nine months since, though left 

 in the tube in which they were stained, are as perfect as at the time 

 they were prepared. After staining, the casts can be mounted in 

 balsam or dammar without undergoing any change. 



Method for Dry Preparations.! — Dr. G. Eiehm, after stating that 

 the method of making the dry preparations recently shown has not been 

 published by its original inventor, describes what he terms a simple and 

 inexpensive process for attaining the same end. 



After being arranged so as to show the required anatomical points, 

 the specimen is hardened, preferably by chromic acid (Mollusca), 

 Midler's fluid, picrosulphuric acid or (when the tendency to shrink- 

 ing is not great) in alcohol. All water must then be extracted with 

 absolute alcohol ; if this is not thoroughly done, shrinkage occurs 

 later. It is then placed in oil of lavender or oil of turpentine 

 (the latter is, however, sensitive to traces of water), and, when 

 quite saturated, extended with pins or otherwise on filter paper 

 and left there for forty-eight hours. The specimen has then a 

 brilliant white colour and maintains its colour and condition if 

 protected from dust. The principle of the method consists in the 

 prevention of decomposition by removal of the water and the pro- 

 tection of every particle from the action of the aqueous vapour and 

 oxygen of the air by an investing film of resinous matter, the 

 result of oxidation of the turpentine or oil of lavender. The cost of 

 preparing such an object as the frog's intestine is about 30 pfennings 

 (3^ pence, English value), and may be reduced by distilling the oil 

 and using it again, and by employing the old absolute alcohol for 

 approximate dehydration of other specimens, an important recom- 

 mendation in the case of museums and other institutions. A dealer 

 in Halle, named Schluter, undertakes to supply specimens of the more 



* Amer. Mori. Micr. Journ., iii. (18S2) pp. 153-4. 

 t Zool. Anzeig., ix. (1881) pp. 672-3. 



