OATTANEO'S METHODS. 379 



drawn in by means of blotting-paper applied at the opposite 

 edge. They are washed by the same process with alcohol of 

 70 per cent._> 90 per cent., and then water. The objects are 

 then stained by a drop of Weigert's picro-carmine, which is 

 allowed to act for from half an hour to two hours in a moist 

 chamber. They are then washed out with alcohol of 70 per 

 cent., followed by 90 per cent, and absolute alcohol, are cleared 

 with clove oil and mounted in balsam. 



For AmoebaB a drop of 2 per cent, solution of chromic acid, 

 which is allowed to act for two or three minutes, gives better 

 results than osmic acid. 



LANDSBEEG (ibid.,^ . 336) treats the organisms with the same 

 reagents, but operates by taking up the organisms separately 

 with a capillary tube and bringing them separately into a drop 

 of the respective reagents. Care must be taken to have a 

 small drop of liquid in the lower end of the tube before 

 bringing it near to the object to be taken up, in order to check 

 the violent rush up of the liquid into the tube. Landsberg 

 recommends that Actinosphserium be mounted in glycerin 

 instead of balsam. 



754. BLANC (ibid., 1883, p. 22) employs for fixing Infusoria 

 a picro-sulphuric acid of the following composition : 



Saturated picric acid solution . .100 vols. 



sulphuric acid . . . 2 

 Water 600 



This liquid is for larvae of Echinodermata, of Medusae, and 

 of Porif era ; for Ehizopoda and Infusoria add two or three 

 drops of 1 per cent, acetic acid for every 15 c.c. of the liquid. 

 The acetic acid is added in order to bring out the nuclei and 

 " nucleoli." Blanc fixes under a cover- glass, notwithstanding 

 the objections of Korschelt. Wash out with 80 per cent, 

 alcohol, followed by 90 per cent, and absolute. Stain with 

 saffron solution ( 192), wash out with 80 per cent, alcohol until 

 the colour is sufficiently extracted, and pass through absolute 

 alcohol into clove oil. 



Blanc recommends the method for the preservation of most 

 microscopic organisms, and in particular for marine Nema- 

 todes, the stain being sufficiently penetrating to pass through- 

 their thick chitinous integument. 



755. CATTANEO'S Methods (Bollettino Sdentifico, iii and iv; 



