CONSTITUTION OF MESOGL(EA OP ALOYONIUM DIGITATDM. 391 



bird's-nest which Kruckenberg (op. cit.) regards as composed 

 of a hyalogen-neossidiu, giving rise on solution to a hyalin- 

 neossin. The mesogloea further resembles the reactions of 

 the edible bird's-nest as described by Green^ in the absence of 

 a cellulose reaction, and in the fact that on boiling with dilute 

 sulphuric acid a pinkish coloratiou, which subsequently 

 darkens, is seen. 



Another feature frequently shown by hyalins, in which that 

 under consideration agrees, is the absence of Millon's reaction. 

 An application of this test micro-chemically to mesogloea shows 

 us that the cells alone stain red. This indicates that the pro- 

 teid extracted by 5 per cent, salt solution (which presents all 

 the characteristic features of a globulin) is located in the cells, 

 and not in the mesogloea ; it need not then detain us. 



The micro-chemistry of hyalogen presents a slight difference 

 from that of mucin. Pieces of mesogloea which yielded no 

 further mucin to lime water were decalcified, and cut with the 

 freezing microtome. Stained with thionin by Reid's method, 

 the purple coloration of the mesogloea only appears under 

 artificial light, recalling the conditions of the basophilic reaction 

 with methylene blue. The endoderm-cells appear blue both 

 with natural and artificial light. 



We shall not err greatly, then, if we describe the organic 

 constituent of the mesogloea as mainly a hyalogen, probably 

 mixed with some amount of mucin. The hyalin obtained 

 from the hyalogen is precipitated on saturation with ammonium 

 sulphate as a gummy mass. 



III. As stated above, after extraction of previously acidified 

 mesogloea with lime or baryta water a small amount of a some- 

 what granular residue is left. Examined under the microscope, 

 it is seen to consist of clumps of globules which yield the 

 xanthoproteic reaction. They recall in some measure the 

 description given by MalP of the appearances of elastin acted 

 upon by acids or alkalies. The substance, however, is not 

 elastin, as is seen by its having no affinity for Victoria blue or 



' J. R. Green, ' Journal of Physiology,' vol. vi. 

 - Mall, ' Anat. Anzeig.,' iii Jahrg. 

 VOL. 37, PART 4. — NEW SEK. D D 



