EXPERIMENTAL ANALYSIS 



various compounds which exhibit this effect at higher dosages. Lettre 

 and his colleagues in a series of papers^^^ have shown that some features 

 are common to the molecules of both colchicine and a few other 

 antimitotic compounds. These, however, are only a small minority 

 of such substances. Nor is much light on the cytological action of 

 colchicine derived from what is known of its various other physiological 

 properties; it provokes haemorrhages in tumours as do bacterial 

 polysaccharides (Boyland and Boyland^^^), it enhances the effects 

 of adrenaline on the whole animal (Raymond-Hamet^*^), it parti- 

 ally inhibits some enzymes, such as xanthine oxidase (Keeser^*^) 

 and interferes at some point in the contraction cycle of striped muscle 

 (Lecomte^^^)*. 



The cytological effects of colchicine are not restricted to the inhibition 

 of the mitotic spindle. Mitotic figures are seen in the liver of the adult 

 rat after an injection of colchicine (Miszurski and Doljanski^^^j . 

 growth in yeast is stimulated by colchicine (Richards^*^), and the 

 chromonemata become more noticeable in the intermitotic nuclei of 

 the cockroach (Ries^*'). Breaks in chromosomes are induced by 

 colchicine in the anthers of Carthamus (Krythe^*^) and in Tradescantia 

 pollen-tubes (Eigsti^*^). 'Bubbling' at the surface of fibroblastic cells 

 in culture is evoked (Miszurski^^*'), and perhaps the most important 

 observation of all, Beams and Evans^^i find that eggs of Arbacia 20 

 minutes after fertilization are more readily stratified by centrifugation 

 in the presence of colchicine. Mitosis in some of these eggs was blocked 

 in early anaphase, the dissolution of the asters was observed, and the 

 cleavage of the ^gg did not occur in their absence. 



More comparative studies of the effects of other mitotic inhibitors 

 acting at high dilutions on various types of cell are greatly needed. One 

 should examine their effects both on protoplasmic consistency and on 

 cleavage in a variety of dividing cells. Colchicine has been shown to 

 have no effect on fission in several Protozoa, nor on locomotion and 

 ingestion in Amoeba (King and Beams^^s). Cornman and Cornman^^i^ 

 observed that Protozoa multiplied in dishes in which Asterias eggs were 

 disintegrating under the influence of podophyllin. 



It is of interest that 2-methyl i, 4 naphthoquinone, which has an 

 inhibitory action on mitosis in tissue cultures (Mitchell and Simon- 

 Reuss^^^) has an opposite effect on the Arbacia egg, causing partheno- 

 genic activation and cytoplasmic gelation (Halaban^^^), though the 

 effects on the tgg of Chaetopterus are again somewhat different (Heil- 

 BRUNN and Wilson^^^). Among substances which inhibit both mitotic 



* Cornman^*'* has shown that a large excess of carbohydrate can partially neutralize 

 the effect on sea-urchin eggs of colchicine and podophyllotoxin. Murray, de Lam, and 

 Chargaff^*'*' find that meso-inositol has a specific eflfect in blocking the action of colchicine 

 on dividing rat fibroblasts in culture. 



