MITOCHONDRIA AND BACTERIA 157 



MOLECULAR SOLUTION 



acid resistant they are stained bluish 

 green. 

 Mitogenic Radiations. It is questionable 

 whether these rays, said to generate 

 mitosis, really exist. A critical and 

 well balanced statement is afforded by 

 Glasser, O., in Glasser's Medical Phy- 

 sics, 7G()-763. 

 Mitosis (G. Mitos, thread). Indirect nu- 

 clear division in which the chromatin 

 forms a thread which breaks up into 

 chromosomes. 



Material should be freshly fixed, less 

 than half hour after removal . But mito- 

 sis can be seen in some tissues 24 hrs. or 

 longer after death, especially if the body 

 is kept at a low temperature but the 

 number is less and the details not so 

 clear as after quick fixation (Mallory, 

 p. 108). Sat. mercuric chloride in 70% 

 ale. plus 5% acetic acid, Zenker's fluid, 

 formalin-Zenker , Bouin's fluid and Flem- 

 ming's strong fluid are satisfactory 

 fixatives but the last named penetrates 

 very badly. 



The most beautiful stain for mitotic 

 figures is safranin light green but the 

 mitoses can be more clearly distin- 

 guished without the green counterstain. 

 Simply deparafnnise and stain sections 

 in aniiin-safranin (Babes), wash quickly 

 in tap water, differentiate in acid alcohol 

 until the resting nuclei arc less intensely 

 colored than the dividing ones, wash in 

 95%, dehydrate in abs. clear in xylol 

 and mount in balsam. 



Another excellent method is to apply 

 the Feulgen reaction for Thymonucleic 

 Acid to sections of tissues preferably 

 fixed in Carney's fluid or acetic subli- 

 mate. This demonstrates thymonucleic 

 acid in the chromatin, and the dividing 

 nuclei, as with safranin, are more deeply 

 stained than the others. This method 

 is displacing the older safranin tech- 

 nique. 



To demonstrate mitosis in whole 

 mounts of epidermis place freshly ex- 

 cised skin (circumcision specimen pre- 

 ferred) in 0.1% aq. acetic acid in the 

 icebox over night. Wash quickly in 

 aq. dest. Strip off the epidermis with 

 needles, stain it like a section with 

 aniiin-safranin or with Harris' hema- 

 toxylin and mount with the outer sur- 

 face uppermost. This technique could 

 probably be adapted to relatively flat 

 epithelia of the respiratory digestive, 

 urinary and genital systems. 



In order to reveal the maximum num- 

 ber of mitotic figures it is important to 

 study the mitotic rhythm of the par- 

 ticular tissue or organ and take tissues 

 at the peak which in the case of the 

 human foreskin is probably between 

 9 p.m. and midnight (Cooper, Z. K. and 



Schiff, A., Proc. Soc. Exp. Biol. & Med., 

 1938, 39, 323-324). 



To experimentally increase the num- 

 ber of mitosis use colchicine which ar- 

 rests the process chiefly in the meta- 

 phase by causing failure of the mitotic 

 spindle to form and function (Ludford, 

 R. J., Arch. f. e.xper. Zellf., 1936, 18, 

 411-441). Consequently as long as the 

 cells are under the influence of colchi- 

 cine — a matter of a few hours only — 

 mitosis begins as usual; but, since it is 

 not completed, the proportion of mitotic 

 figures to resting nuclei is temporarily 

 greatly increased. Sodium cacodylate, 

 auramine and other substances listed by 

 Ludford likewise influence mitosis. 

 For checks on the method of estimating 

 growth by counting arrested mitoses, 

 see Paletta and Cowdry (F. X. and 

 E. v.. Am. J. Path., 1942, 18, 291-311). 

 Aisenberg (E. J., Bull. d'Hist. Appl., 

 1935, 12, 100-122) has found that mitosis 

 of epidermal cells is arrested in the 

 metaphase simply by passing a ligature 

 around a frog's leg and keeping the foot 

 in distilled water. The mitoses ac- 

 cumulate in large numbers but continue 

 when released from the hypotonic 

 environment. Aisenberg {ibid. 1936, 

 13, 265-286) also discovered low concen- 

 tration of ethyl alcohol to stimulate 

 mitosis, 0.4-0.8 M to arrest in meta- 

 phase, 1.2-1.5 M. to cause gelatinization 

 of mitosis and higher concentrations to 

 kill the cells. 

 Molecular Film Technique, see Taylor, H. 

 S., Lawrence, E. 0., and Langmuir, I., 

 Molecular Films, the Cyclotron and the 

 New Biology, Rutger's University Press, 

 1942, 95 pp. 

 Molecular Solution is the molecular weight 

 of the substance in grams made up to 1 

 liter with aq. dest. Thus M oxalic acid 

 (COOH)2-2H20 is 126 gms. with aq. 

 dest. added to 1 liter; but A^ oxalic acid 

 is half of this concentration. See 

 Normal Solutions. 



The molecular weight expressed in 

 grams is called the gram-molecular 

 weight or mole. 



Millimole is 1/1000 of a mole. 



Milligram equivalent (milliequiva- 

 lent). The equivalent weight, the 

 gram-equivalent, or the equivalent of a 

 substance is the weight in grams which 

 in its reaction corresponds to a gram 

 atom of hydrogen , or of hydroxyl , or half 

 a gram atom of oxygen, or gram 

 atom of a univalent ion. Milliequiva- 

 lent is 1/1000 of the equivalent weight, 

 i.e., the equivalent weight of sodium 

 carbonate is ^ the molecular weight, or 

 53.0. Therefore, the milliequivalent 

 (m.e.) or the weight in 1 ml. of normal 

 solution is 0.0530 gm. 



