CHORIOALLANTOIC MEMBRANE 



64 



CHROMOLIPOIDS 



and the membrane exposed. The 

 chorioallantois is cut with a pair of fine 

 curved-end scissors, removed, fixed in 

 Zenker's sohition (with 5% glacial 

 acetic). After washing, dehydrating, 

 clearing in xylol, and imbedding in 

 paraffin, it is sectioned and stained. 

 Various staining techniques can be used 

 depending on the organism inoculated. 

 In general, for fungi, Loeffler's meth- 

 ylene blue and eosin have given satis- 

 factory results. For experimental tech- 

 nique of growing mouse sarcoma in 

 chorio-allantoic membrane, see Jacoby, 

 F., McDonald, S. andWoodhouse, D. L., 

 J. Path, and Bact., 194.3, 55, 409-417. 



Chor's Modification of Ranson's pyridine 

 silver method was worked out in our 

 laboratory to show alterations in motor 

 end plates in biceps and triceps of mon- 

 keys in experimental poliomyelitis 

 (Chor, H., Arch. Neurol. & Psychiat., 

 1933, 29, 344-357). Fix in 1% ammonia 

 water (28% Merck) in 95% alcohol for 

 24 hrs. Wash in aq. dest., f hr. Pyri- 

 dine, 48 hrs. Wash in 8 changes aq. 

 dest. during 24 hrs. 2%aq. silver nitrate 

 in dark at room temperature, 72 hrs. 

 Reduce 6-8 hrs. or over night in: pyro- 

 gallic acid, 4 gra.; aq. dest., 95 cc; 

 formalin, 5 cc. Dip in water and trans- 

 fer immediately to 95% alcohol for a few 

 seconds. Place tissue on slide with 

 longitudinal markings of fibers visible. 

 Add a second slide and squeeze gently. 

 Trim edges with sharp knife so that neat, 

 flat blocks result. 96% alcohol, 30 min. 

 Absolute alcohol, 2 changes, over night. 

 Xylol, 10-12 hrs. until blocks are clear. 

 Imbed in paraffin 8 hrs. changing re- 

 peatedly each hr. for first five. Cut 

 serial sections 10/x. Mount in neutral 

 balsam. Nerves, dark brown or black; 

 muscle and connective tissue, j'ellow. 



Chrom Blue GCB, see Gallocyanin. 



Chromaffin Reaction (chromic salts -f L. 

 affinis, akin). Brown coloration when 

 treated with fixatives containing bi- 

 chromate. In adrenal medulla adrenalin 

 is revealed by this brown color but the 

 reaction can also be elicitated by po- 

 tassium iodate and is not altogether 

 specific for adrenalin. Lison (p. 147) 

 advises fixation in Formol-Miiller or in 

 5% potassium iodate containing 10% of 

 formol. After the usual fixations chro- 

 maffin substances can be demonstrated 

 simply by treating the sections for a few 

 hours with 3% aq. bichromate or iodate 

 of potassium (Lison). See Vulpian Re- 

 action and Osmic Acid. 



Chromatin Filaments. The studies of 

 Claude, A. and Potter, J. S., J. Exper. 

 Med., 1943, 77, 345 and of Mirsky, A. E., 

 and Pollister, A. W., Biological Sym- 

 posia., 1943, 10, 247-260 indicate that 



chromatin is almost wholly made up of 

 fibrous nucleoprotein. By extraction, 

 precipitation and centrifugation the 

 chromatin filaments can be collected. 

 They are of very uniform diameter, 

 like chromosomes, are very resistant to 

 deforming mechanical injur,y, can easily 

 be stained with acetocarmine are given 

 a positive Feulgen reaction. Mirsky 

 and Pollister favor the view "that 

 chromatin is largely, if not entirely, a 

 complex of highly polymerized desox- 

 yribose nucleic acid with a basic protein 

 of either the protamine or histone 

 type." 



Chromatin Stains. The most specific stain 

 for basic chromatin is methyl green. 

 Bismark brown is less so. Safranin is 

 useful for chromatin if a red coloration 

 is desired as in the safranin-light green 

 combination. Tests for Iron and Thymo- 

 nucleic Acid are listed separately. 

 See Idiochromatin, Linin, Chromosomes 

 and Nucleolus. 



Chromatolysis of nerve cells investigated by 

 absorption spectra of Nissl bodies 

 (Gersh, I., and Bodian, D., Biological 

 Symposia, 1943, 10, 163-184). 



Chromatophores. These, when present in 

 the dermis, are also called melanoblasts, 

 see Dopa Reaction for their demon- 

 stration. 



Chrome Violet CG (CI, 727). A carbo.xyl 

 derivative of pararosolic acid. 



Chromic Acid is purchased as the red crys- 

 tals of chromic anhydride which dissolve 

 easily in water forming chromic acid. 

 The crystals should be kept in a bottle 

 with closely fitting glass stopper because 

 they are highly deliquescent. Alone in 

 very dilute solution chromic acid is 

 helpful in Maceration. When applied in 

 aqueous solutions of about 1% to a slice 

 of fresh adrenal it produces a brown color 

 in the medulla known as the chromaflin 

 reaction. In mixtures with other chem- 

 icals it was more used as a fixative 50 

 years ago tlian today but in Perenyi 

 Fluid it is recommended strongly by 

 Lee (p. 32) for embr3^os, segmenting eggs, 

 etc. It is also a component of Flem- 

 ming's fluid. 



Chromidial Substance, a designation often 

 applied to basophilic cytoplasmic ma- 

 terial supposed to be of nuclear origin 

 and therefore to resemble theextranu- 

 clear chromatin (chromidia) of protozoa. 

 It is nongerminal chromatin or tropho- 

 chromidia in contrast to germinal or 

 idiochromidia (G. idios, individual, 

 one's own). See Nissl bodies. 



Chromolipoids. In contrast to the caro- 

 tinoids, which are hydrocarbons, the 

 chromolipoids are fats or derivatives of 

 fats themselves colored. They occur 

 frequently especially in nerve cells, in- 

 terstitial cells of the testicle and in the 



