138 SUMMARY OF CURRENT RESEARCHES RELATING TO 



after half an lioiir in fresh sea-water were as active and healthy as if 

 nothing had happened. The experiment fails, however, for fishes 

 and Mollnsca, and Crustacea only endure it for a short time. 



In addition to the value of this method for photography, it will 

 prove useful for distributing living marine animals and for physio- 

 logical jmrposes. 



Corallin as a Microscopical Reagent.* — I. Szyszylowicz distin- 

 guishes the various descriptions of mucilage occurring in the vegetable 

 kingdom as follows: — 1. Mucilage, i.e. substances which swell in 

 water, are nearly allied chemically to cellulose, are coloured blue by 

 iodine and sulj)huric acid or zinc chloride, and which yield oxalic acid 

 when boiled with nitric acid ; examples, salep, Symphytum, &c. 

 2. Gums, which also swell in water, dissolving at the same time, are 

 not coloured blue by iodine even on addition of suljihuric acid and 

 zinc chloride, and which yield mucic acid when boiled with nitric 

 acid ; examples, TiJia, Osmunda, &c. 3. Mixtures of mucilage and 

 gum, which the author calls gum-mucilage ; and which combine the 

 properties of the two first kinds ; these are the most common in the 

 vegetable kingdom ; examj)les, Linum, PJantago, Althcpa, &c. At 

 present we have no microscopical reagent for gum, mucilage, or gum- 

 mucilage, except the property of swelling, and the stronger refringence 

 than the surrounding substances ; but these are not always sufficient. 



Corallin (sometimes called rosolic acid) is obtained by the action 

 of sulphuric acid on phenol in the presence of oxalic acid, and is 

 strictly a pigment composed of aurin and rosolic acid. The author 

 employs it only dissolved in sodium carbonate, when it is of a purple- 

 red colour not changed by exposure to light. The reagent acts difier- 

 ently on the mucilage derived from starch, as in the tubers of Orchidese, 

 and on that derived from cellulose, as in the root of Symphytum. 



The colour imparted to starch-mucilage by corallin is remarkably 

 diu'able ; even long-continued boiling in alcohol does not cause any 

 change, which is the more characteristic from the cell-walls and the 

 protoplasm remaining perfectly clear. Cellulose-mucilage is also 

 coloured by corallin, but the colour is destroyed by cold, and still more 

 by hot alcohol. The pigment has no efi"ect whatever on gum. Gum- 

 mucilage is more or less coloured, the shade and permanence of the 

 colour depending on the proportion of the two ingredients. The re- 

 agent enables one to detect the smallest quantity of mucilage, and its 

 power of swelling, which has not been the case before. It is of 

 esj)ecial value in the examination of the callus in sieve-tubes. In 

 similar cases Eussow uses anilin-blue to distinguish the callus-plate ; 

 but the author maintains that corallin produces a better result when 

 the callus is beginning to swell or is already dissolved. 



The preservation of preparations coloured by corallin is not 

 always possible. The author has preserved very beautiful prepara- 

 tions from starch-mucilage in Canada balsam, but others, and espe- 

 cially those with gum-mucilage, have not been so successful, the 



* Osobne odbicie z Kozpran Akad. Umiej w BLrakowie, x. (1882). See Bot. 

 Ceiitralbl., xii. (1882) p. 138. 



