504 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the colour becoming sensibly paler at a temperature of 50-G0° C, and 

 reappearing on cot)ling. The solution of iodine used was as follows : — 

 distilled water 45 gr., crystallized potassium iodide 0'3 gr., crystal- 

 lized iodine 0*1 gr. 



Glycogen is soluble in water, giving a white opalescent milky 

 solution, which is coloured blue by iodine with precisely the same 

 shade as glycogen derived from a dog. Treated with Trommer's 

 reagent it assumes the blue colour of copper hydrate without reducing 

 it on ebullition. Boiled for 20 minutes with very dilute sulphuric 

 acid, the solution loses its property of being coloured by iodine and 

 acquires that of reducing copper oxide. The same action is produced 

 by saliva. The aqueous solution is dextrogyrous. 



By tracing the passage of glycogen from one part of the plant to 

 another, the author convinced himself that it plays the same part in 

 the economy as starch in other classes of plants, and that it is the 

 first visible product of the absorption of carbon. It is usually most 

 abundant towards the base of the fungus, in the vicinity of the soil. 

 Its quantity is greatest at early periods of growth of the fungus; 

 after this has attained its full growth it gradually disappears, probably 

 from the eflcct of respiratory combustion. 



With regard to other carbohydrates present along with glycogen, 

 the author found that glucose and diastase are less widely distributed 

 in fungi than in starch-producing plants ; while manuite is not less 

 frequent than glycogen, and is often present in considerable quan- 

 tities. He concludes that mannite is the form in which the carbohy- 

 drates pass from one part of the plant to another. He further details 

 several points of analogy between the behaviour of starch and of 

 glycogen, and concludes that their function is the same. In a few 

 species of fungi (as Scleroderma viiJgarc) glycogen appears to be 

 entirely wanting at all periods of their growth. 



Spectroscopic Examination of Photogenic Fungi.* — Dr. F. 

 Ludwig finds that for the examination of the spectra of phosphorescing 

 fungi, e. g. A(/ar{cns mellcus, Xylnria liiipoxylon, Micrococcus PMi'igerl 

 (to which he attributes the phosphorescence of sea-fish, &c.), the even- 

 ing is the best time, as tlie eye is free from all disturbing influences, 

 which atTcct it in daylight, and the phosphorescence is more marked. 

 The Sorby-Browniug Micro-spectroscope was used for the investiga- 

 tions. The following example will serve to illustrate the line of 

 research. 



Trnmetcs pini. Several of the clearest pieces of phosphorescing 

 mycelium were placed under the miero-siiectroscope in a quite dark 

 room with closed windows. The spectrum was very faint and with- 

 out defiuite colour. At first only a weak bluish shimmer was seen, 

 but after two hours' stay in the dark the outline of the spectrum was 

 distinct. At this time a great number of dark lines were noted, and 

 a broad dark band in the otherwise clear spectrum. By comparing 

 with the spectrum of a lighted candle tlie commencement of the phos- 

 phorescence spectrum was found to be in the -clear blue, from which 

 it extended into the ultra-violet. The dark lines were iu the clear 



* Ztitsthr. f. WLss Mikr., i. (1884) p. 181. 



