432 SUMMARY OF CUERENT RESEARCHES RELATING TO 



in order to complete the decolorizatiou, and that the alcohol used for 

 the dehydration should contain four drops of glacial acetic acid to 

 the ounce. 



Fixation and Staining of Chondriosomes.* — A. Maximow recom- 

 mends the method of Champy with the " post-chromisation " of Beuda. 

 The fragments of tissue are placed for twenty-four hours in a mixture 

 of seven parts of 1 p.c. chromic acid, seven parts of o p.c. bichromate 

 of potash, and four parts of 2 p.c. osmic acid. AVash in water and 

 place for twenty-four hours in two parts of acetic acid, and one part of 

 1 p.c. chromic acid. Wash again for half-an-hour, and place for three 

 days in a solution of 3 p.c. bichromate of potash. Wash once more. 

 Embedding in paraffin gives better sections of chondriosomes than 

 celloidin embedding. The staining method of Kull is considered the 

 best and consists of staining at first with acid fuchsin (Altmann), then 

 thioniu, and differentiating with aurantia. The chondriosomes are by 

 this method stained a deep red, while the nuclei take on a purple hue. 

 The protoplasmic ground substance is stained a clear yeUowish grey. 



(5) Mounting', including- Slides, Preservative Fluids, etc. 



Substitute for Canada Balsam. f — 11. Borrow states the gum from 

 Finns ta't/a is a g(jod sul;»stitate for Canada balsam. When prepared 

 for use it has a refractive index of al)out 1 • ()2(i. This makes it specially 

 useful for mounting diatoms. It is prepared as follows. Put the gum 

 into a wide-mouthed bottle and add just sufficient alcohol to cover it. 

 When dissolved pour off the clear part into another bottle and add oil 

 of cassia in the proportion of one of cassia to three of gum. To use it 

 for mounting diatoms, dry the specimens on a cover-glass in the usual 

 way, place on the hot-plate, and heat until bubbles are caused. When 

 these cease to appear, apply a lighted match quickly, which will clear all 

 the remaining Inibbles. Now push the cover-glass on to a cold-plate of 

 iron or earthenware, when the gum will immediately harden. Warm 

 the slide and place on it the cover-glass. The gum will melt and allow 

 the cover to settle down, or slight pressure may be applied. Put on the 

 cold-plate again. In a minute or so the gum which has oozed out may 

 be chipped off with a sharp-pointed knife. 



f6) Miscellaneous. 



AmoebaB in Pyorrhoea alveolaris.:!: — J. Mendel has investigated the 

 question of the pathogenicity of the Entanueba hucccdis in infective 

 conditions of the mouth, and has come to the following conclusions. 

 The presence of amoebfe in the buccal cavity of man is a commonly 

 observed circumstance, and is not exclusively characteristic of the 

 affection known as Pyorrhaia alveolaris. Amoebte are however met 

 with in nearly all cases of the disease, and are found in all mouths, in 



* C.R. See. Biol. Paris, Ixxix. (1916) pp. 462-5. ■ 

 t English Mechanic, June 23, 1916, pp. -131-2. 

 X Ann. Inst. Pasteur, xxx. (1916) pp. 286-97. 



