294 SUMMARY OF CURRENT RESEARCHES RELATING TO 



sharply the nuclei and the nucleoli, and if not in excess, it never 

 injures the protoplasm. Thus prepared, the liquid is preferable to 

 osniic acid, because the organisms being perfectly killed or fixed, it 

 allows of a surer and more regular colouring, if care is taken to 

 choose a suitable colouring matter. 



Dr. Blanc does not fix the animals until they are covered with 

 the cover-glass, a plan also recommended by Korschelt. This method 

 is very advantageous and easy ; for, in spite of Landsberg's opinion, 

 the organisms are quite as well impregnated by the acid solution as if 

 in a watch-glass. 



The length of time during which the objects should be subjected 

 to the action of the solution, varies according to the size or number 

 of individuals under the same cover-glass ; but it is not until they 

 have all taken a yellowish colour that the preparation can be con- 

 tinued with success. The picro-sulphuric acid is then removed by 

 80 per cent, alcohol, renewed until the yellow colour has completely 

 disappeared, then 96 per cent, alcohol is substituted, and finally 

 absolute alcohol. The organisms being hardened, their staining may 

 be proceeded with. For that purpose an alcoholic solution of safranin 

 is preferable; 5 gr. of safranin are dissolved in 15 cc. of absolute 

 alcohol, and having stood for some days, the solution is filtered and 

 diluted with half its volume of distilled water. This solution is pre- 

 ferable to picrocarmine, because the colouring is more quickly 

 effected and may be regulated according as it is desired to bring out 

 the protoplasm or the nuclei. 



After the object has been sufficiently stained it is washed in 

 80 per cent, alcohol, renewed until no clouds of colour appear, when 

 the 80 per cent, alcohol is replaced by absolute alcohol and the latter 

 by oil of cloves. Safranin being soluble in alcohol a certain quantity 

 of the colouring matter will natm'ally be removed by the washing with 

 80 per cent, alcohol ; but by substituting more or less rapidly the oil 

 of cloves for the alcohol, the colour may be regulated; that is, a 

 more or less intense colouring of the protoplasm around the nucleus 

 can be obtained. 



The method can also be recommended for marine nematodes, 

 whose thick chitine is not an obstacle to colouring by the alcoholic 

 solution of safranin.* 



Preservative for Fungi.f — Three years ago M. E. Banning in- 

 vented what she thinks a very good and cheaj) liquid for the preser- 

 vation of fungi, composed of the following ingredients : 4^ oz. of 

 common salt, 5 oz. of pulverized alum, and 1 quart of w^hite wine 

 vinegar. Mix thoroughly, and keep in a wide-mouthed glass jar. 

 Brush off" any dirt that clings to the fungus, and droj^ the freshly- 

 gathered i)lant into the liquid. 



A large jar of plants that were collected in the summer of 1879 

 are now in a perfect state of preservation. They have diminished 



* Dr. C. O. Whitman (Ainer. Nat., xvii. (1883) p. 458) says that " the process 

 of decoloration is not entirely arrested by the application of clove oil, contrary to 

 Blanc's assertion, hence it should be replaced by Canada balsam as early as 

 possible." 



t Bull. Torrey Bot. Club, ix. (1882) p. 153. 



