246 SUMMARY OF CURRENT RESEARCHES RELATING TO 



solution : saturated alcoholic solution of Rosanilin-violet 2 drops, satu- 

 rated aqueous solution of metliylen-blue 1 drop, distilled water 10 c.cm. 

 The solution must be freshly prepared before use, and for many purposes 

 should be used of double strength. For staining the smears, the solu- 

 tion is allowed to act for 1-2 minutes, and heated until it vaporises. 

 The preparation is then washed with water, dried, and mounted. 



Inverse Staining.*- — B. Nemec gives the following procediu'e, which 

 is chiefly useful for demonstrating the presence of starch grains. By 

 this method the usual effects of staining, reagents is reversed, i.e. the 

 cytoplasm and contents are coloured, while the nucleus and chromosomes 

 remain unsUiined. 



The material was fixed in picric-acetic-sulphuric acid, or with chro- 

 mic acid, or with Flemming's fluid. It must be noted that osmic acid 

 preparations must be treated with turpentine or peroxide of hydrogen. 

 The sections are transferred from water to 2 p.c. tannin solution for 

 10-60 minutes. After washing they are placed for 5-15 minutes in 

 1'5 p.c. tartrate of antimony solution. The sections are then washed 

 in water frequently changed and then are placed in the stain, e.g. 

 aqueous gentian-violet, for half an hour or longer. On removal they 

 are washed for 5 minutes and then passed through upgraded alcohols to 

 absolute, wherein they remain until they no longer give up any dye. 

 When dehydrated (about 5 minutes) the sections are passed through 

 turpentine to xylol and mounted in balsam. 



It may be noted that the longer the sections remain in the mordant 

 (tartrate of antimony) the deeper the cytoplasm will be stained. 

 Double stained preparations may be obtained by staining the material 

 en masse with paracarmin, or by staining the sections with acid-fuchsin 

 and following this by the inverse method. 



Studying the Anatomy of the Kidneys of Gobiesocida.f — F. Guitel 

 adopted the following complicated procedure in his researches on the 

 kidney of Leiiadn(/astei\ etc. 



The animal, having been killed with chloroform, was opened under 

 water along the ventral aspect and the digestive tube removed, care 

 being taken not to injure the kidneys. The body cavity is kept open 

 with a piece of wood and the animal immersed in saturated sublimate, 

 to which 1 p.c. acetic acid is added. After from 2-5 minutes the 

 animal is washed in 70 p.c. alcohol, or in water, and then placed in 

 70 p.c. alcohol containing 1 per thousand of iodin for 20-60 minutes. 

 The iodin-alcohol solution must be frequently renewed. The kidneys 

 are next removed, but again placed in iodin-alcohol, and afterwards in 

 DO p.c. alcohol. Arrived at this stage the material may be kept in 

 alcohol for further investigation. Sections of the material were stained 

 with alum-carmin, or with Heidenhain's hsmatoxyHn. 



Injections of the fixed material prepared as above stated gave fruitful 

 results in the study of the canalicular system. The injection mass used 

 was metagelatin stained with soluble blue. The kidneys to be injected 

 are cut transversely a few millimetres in front of their posterior extremity, 



* Ber. Deutsch Bot. Gesell., xxiv. (1906) pp. 528-31. 

 t Arch. Zool. Exp6r., v. (1906) pp. 505-608 (5 pis.). 



