Pharmacology 189 



Ai i^iesciit. no dear relation can be discovered between the in- 

 hil)ition ot mitotic growth and tlie colchicine-leukocytosis, and clearly 

 ncAV Avork is badlv needed in this field. Some facts are of interest 

 ho^\e\ er. 



It has Ixen disco\ered that in leukemic patients and in normal 

 men a single dose of colchicine (2 mg.) may increase considerably the 

 ntunbei- of platelets. The bone-marrow megakaryocytes do not change 

 in number, but there is evidence of a greater |)latelet-building activity 

 by their c\ toplasm.-^"' ^^ In essential thrombopenia, where megakaryo- 

 cvtes are present but appear to be unable to produce platelets, this 

 effect of colchicine was not found. It is evidently not related to 

 mitosis. 1)11 1 may be similar to some other membrane changes induced 

 by the alkaloid (Chapter 4) . 



Some recent work attempts to relate the bone-marrow changes and 

 leukoc\ tosis. This is often preceded by a transient period of leuko- 

 penia. Avhich appears to ha\e no causal influence on the leukocytosis."" 

 Bone-marroA\' studies in mice and rabbits all {(Mifirm the increase 

 of arrested metaphases, which is about 15-fold in the rabbit after 15 

 hours. The erythroblastic cells become progressively more numerous 

 than the granuloblastic; the increase is from 10-15 per cent to more 

 than 60 jjer cent in mice. The immature cells increase in proportion, 

 because the adult cells leave the marrow. There is no visible relation 

 between this phenomenon and the mitotic changes.'" However, re- 

 peated daih injections of 12 /^g. of colchicine increase considerably 

 the number of leukocytes in the blood of mice (more than 250,000 per 

 cmm.) . It has been suggested"" that these changes may be the con- 

 secjuence of a central nervous stinudation of the bone marrow. This 

 is in line with more recent pharmacological data (see above) and 

 merits close attention. 



rhe following changes of blood cells after colchicine may be 

 mentioned here, though an explanation is not evident. Young rats, 

 aged 1 and 3 days, de\elop anemia, and a single injection decreases 

 the red blood cell diameter." ^ 1 hese two facts may bear some relation 

 to the decrease in the numbers of reticulocytes, which ha\e a larger 

 diameter than average red blood cells. An increase of "monocytoid" 

 leukocvtes in a case of fatal human poisoning'^-' parallels the ob- 

 servation of abnormally great nmnbers of histiocytes in guinea-pig 

 tissues after repeated injections.''" Several imjjortant data on blood 

 cells studied by culiine //? I'ltro with the hel}) of colchicine will be re- 

 ported in Chapter 9. 



j-^-2: Ski)i. Iidir. <nui frtit/icrs. Colchicine arrests the mitoses in 

 the hair follicles in mannnals. Inhibition of haii' growth tan be seen 

 in rats in the \ icinit\ of colchicine injections, and loss of hair has been 

 found in human intoxication.^' In birds, similar changes may be ex- 



