IDIOCHROMATIN 



162 



INDIGO 



concentrated the index is higher al- 

 though the total amount of bilirubin in 

 the circulation may not be elevated. 

 See much more adequate description 

 by Wintrobe, M. M., Clinical Hematol- 

 ogy. Philadelphia: Lea & Febiger, 

 1942, 703 pp. 



Idiochromatin (G. idios, one's own, pe- 

 culiar). The chromatin concerned par- 

 ticularly with reproductive functions 

 such as chromosome formation con- 

 trasted with nutritive trophochromatin 

 (G. trophe, food, nourishment). There 

 is no special technique for it. 



Illumination. For microscopic work the 

 lighting is of great importance. Direct 

 visible light can best be obtained from 

 various electric microscopic lamps on the 

 market. Only when the light is more 

 intense than that required for routine 

 purposes can it be properly employed 

 for dark field examination or for polari- 

 zation. Therefore an intense source 

 should be available. The intensity can 

 be reduced to optimum by using an 

 iris diaphragm. When it is desired to 

 deliver light into the body to a position 

 behind living tissues or organs for 

 transillumination the Quartz Rod tech- 

 nique is suggested. 



Even to make the light equivalent in 

 quality to that from the white cloud on 

 a bright day, that microscopists used to 

 search for, is quite unnecessary. If the 

 light is too much screened by "day- 

 light" or other glass its intensity will 

 be impaired. Green light was recom- 

 mended quite enthusiastically about 20 

 years ago. But it is difficult to secure 

 green light of the necessary intensity 

 and it is unpleasant to work with. 

 Ultraviolet light, which permits higher 

 resolution and is selectively absorbed 

 especially by nucleoproteins, is used 

 occasionally for Ultraviolet Photomicro- 

 graphy. The objects, however, can of 

 course not be seen directly so that to 

 photograph them is a hit and often miss 

 experience, though it is possible to 

 focus on a fluorescent screen. The 

 principal use of ultraviolet light is in 

 the Fluorescence Microscope by which 

 the structures giving off fluorescence 

 can be viewed in a dark background at 

 high magnification. 



Imbedding, see Celloidin, ParafiBn, Glycol- 

 Stearate, Rubber Paraffin, Ceresin, 

 Double and Gelatin for imbedding 

 preparatory to sectioning. The Mount- 

 ing of sections and whole tissues is a 

 kind of imbedding. 



Immersion Oils. A special grade of cedar 

 oil is usually emploj'ed for oil immersion 

 objectives. Mineral oil is also sold for 

 this purpose. If a refractometer is not 

 available Lillie (p. 6) recommends ad- 



justment of the index of refraction of 

 the mineral oil by the addition to it of 

 alphabromonaphthalene gradually to 

 the point where a white glass slide im- 

 mersed in the oil can no longer be seen 

 through the oil. It should be N A 1.515 

 to 1.520. For darkfield work he uses a 

 mixture of 4 parts of "heavy" mineral 

 oil with one part of alphabromonaph- 

 thalene. Cedar oil as supplied for this 

 purpose may easily get too thick by 

 evaporation. It should never be left to 

 harden on the objective but should 

 always be brushed oft" with lens paper 

 immediately after use. If it does 

 harden on the objective, condenser or 

 slide wet the lens paper with xylol 

 which will dissolve the oil when it is 

 gently applied. See Lens Paper. 



Immunization of monocytes against foreign 

 erythrocytes with phagocytosis of the 

 latter (Bloom, W., Arch. Path, and Lab. 

 Med., 1927, 3, 608-628). 



Impedence, see Electrical Resistance. 



Imperial Red, see Eosin B or bluish. 



Imperial Yellow, see Aurantia. 



Impression Preparations, see Smears. 



Inanition, see Fasting. 



Inclusion Bodies are any substances in- 

 cluded in a cell, tissue or organ. There 

 is the implication that the substance is 

 included from without, that is to say, 

 it is of extraneous origin. But the 

 designation is so loosely used as to be 

 almost meaningless. It is applied to 

 droplets of fat, ingested pigments, 

 remnants of phagocytosed materials, 

 bodies developed in cells as a result of 

 virus action and so forth. The virolo- 

 gists have taken over the designation 

 from normal cytology in which it is 

 used less and less. In certain virus 

 diseases inclusions form in the nucleus, 

 in the cytoplasm or in both (Cowdry, 

 E. V. in Rivers' book on Virus Diseases, 

 Baltimore, Williams & Wilkins, 1928, 

 pp. 113-154). 



Since the nucleus is shielded from the 

 environment by the cytoplasm its reac- 

 tivity is restricted and the materials 

 available for the formation of nuclear 

 inclusions are also limited as compared 

 with those in the cytoplasm. Conse- 

 quently the composition of nuclear in- 

 clusions in virus diseases is more uni- 

 form than that of cytoplasmic inclusions. 

 See Nuclear and Cytoplasmic Inclusions 



Indamin Dyes. Methylated amino deriva- 

 tives of indamin. Bindschedler's green 

 and toluylene blue. 



India Ink, see Higgins'. 



Indian Blue 3 RD, see Naphthol Blue. 



Indicators, see Hydrogen Ion and Oxidation 

 Reduction Potential indicators. 



Indigo, a fine blue dye produced from the 

 leaves of Indigofera tinctoria, employed 



