540 SUMMARY OF CURRliNT RESEARCHES RELATING TO 



surface of tho scctious, Tlicy arc thou i)laco(l in an aqucons solution 

 of chemically pure sulphurous aciil, in whicli they lose the coh)uring 

 matter iu parts. They are next washed in distilled water, and 

 again placed iu the permanganate solution for 3-4 seconds, and after- 

 wards in the sulphurous acid. Tlie process is repeated uutil the 

 sections are colourless, and they arc then dehydrated, and mounted in 

 the usual way. 



Tho hacilli of syphilis, leprosy, and tuberculosis arc not de- 

 colorized by this method ; all other bacteria arc. The bacilli of 

 syphilis are decolorized by nitric acid. They appear as straight, 

 curved, or irregularly bout rods, SS-i\ yu, in length, and under 

 high powers their surface appears undulatory and slightly notched. 

 Each bacillus contains 2-4 oval spores. The bacilli wore always 

 inclosed in cells varying from a trifle larger than, to double tho size of 

 a white blood-corpuscle, in the midst of tho infiltration. The bacilli 

 are found in them singly, in groups of two to nine or more, or in irregular 

 confusion. 



Methods for observing Protoplasmic Continuity.*— Mr. T. Hick, 

 in an article on protoplasmic continuity in the Fucacca;, says that he 

 found the following methods, as a rule, furnished such favourable 

 results, that, for the guidance of those who may wish to verify his 

 statements, ho gives them in full. 



To obtain a general view of the structure of the thallus of the 

 plant under investigation, thin sections were placed in fresh water for 

 a few minutes and then stained with methyl-green acidulated with 

 acetic acid. After well washing with water or acetic acid, the sections 

 were put for a short time — varying in difterent cases— into alum- 

 carmine. They w^ere again well washed with water, swollen with 

 strong ammonia, and mounted in glycerin. Sections prepared in this 

 way turn out in a very pretty condition, the protoplasmic structures 

 being coloured green and the framework a pale pink or violet. Before 

 swelling with ammonia the sections must be thoroughly washed, to 

 remove all traces of alum, as otherwise the ammonia will cause a 

 precipitate of aluminic hydrate to be thrown down. 



For the determination of more refined details tho sections were 

 treated as follows: — Having been washed with fresh water, they were 

 stained -with an aqueous solution of saliranin ; again washed with 

 water and swollen with strong ammonia; and finally moimted in 

 glycerin. Thus prepared, the sections showed the protoplasts of a 

 pink colour and their envelopes yellow, deepening here and there to 

 brown. 



Still more satisfactory results were, however, obtained thus: — 

 Sections were soaked for from 3 to 12 or 20 hours in a mixture of 

 strong sulphuric acid 1 part, and water 3 parts. They were then 

 washed, stained with satfranin as in the preceding process, and 

 mounted in a mixture of glycerin and ammonia. If the ammonia is 

 employed to swell the sections before mounting, they become so 

 much disintegrated that it is then impossible to transfer them to a 

 slide. 



♦ Jouru. of Bot., xxiii. (1885) pp. 97-102. 



