Cellular Growth 



115 



phase II merges ^vith the second c-anaphase II. All the chromosomes 

 remain within one cell, so that instead of a tetrad of 4 cells, a monad 

 results with all 4 sets of chromosomes contained within one cell (Fig. 

 4.3) . The monad is tetraploid. C-telophase II concludes the c-meiosis 

 with unraveling and loss of the stainable structure.^^^ 



The full c-meiosis has been sketched briefly without taking into 

 consideration deviations and abnormalities caused by different con- 

 centrations, exposure, and stage at which the drug acts. Abnormal 

 diploid, tctrajjloid, hexaploid, and octoploid microspores may be 

 found, as was noticed for Tradescautia and Rlioeo (Fig. 4.3) .-'* Poly- 

 nucleate cells were produced from certain members of the Aloinae^-- 

 and these cases arose from a treatment that probably began in pro- 

 phase of mciosis. 



Reduction divisions in Carthamus tlnctorius L. were treated by a 

 special technique in Avhich the entire inflorescence was treated. "^ 

 Under these conditions 10 to 17 pollen grains appeared within a 

 single pollen mother cell (Fig. 4.5) . Most grains had a nucleus, ex- 

 cept for the very small grains. In view of the fact that this species is 

 dicotyledonous, while the major descriptions of c-meiosis were made 

 from monocotyledonous types, these differences may be in order. The 

 simultaneous formation of tetrads within a pollen grain of the dicoty- 

 ledons may accomit for the variations. Carthamus and Allium show 

 certain fundamental differences. 



The aftereffects of colchicine point out a possible influence upon 

 pairing at meiosis in Antirrhiumn as long as 6 weeks and possibly 



TABLE 4.3 

 Action of Colchicine on Chiasmata in Fritillaria 

 (After Barber, 1 940) 



up to 15 weeks after treatment ol the plant.'-"' An increase in luii- 

 valents was 37 per cent among the treated plants compared with con- 

 trol. ^-^ A time lapse of such long duration between treatment and 

 the colchicine-effect is of particular interest. Whether the colchicine 

 is retained in the plant or the chromosomal mechanism is specifically 

 affected was not determined. Similar meiotic irregularities were found 



