58 Colchicine 



cessfully for maize in 1932,*- after which time other laboratories fol- 

 lowed Randolph's general method. This is a brief history of poly- 

 ploidy through artificial means before the colchicine era began. That 

 important period made work with colchicine more fruitful than it 

 otherwise would have been. Sudden attention to colchicine almost 

 blotted oiu the facts that polyploidy induced by several techniques 

 had been well developed before 1937. 



The vast literatme-^-^ dealing with polyploidy in plants is discussed 

 in subsequent chapters. 



2.j-^: Polyploidy in animals. Polyploidy in animals has also re- 

 ceived attention for a long time but success with artificial induction 

 has been limited. The introduction of colchicine did not achieve the 

 success found among many projects with plants. 



Temperature shock-cold treatments with newly fertilized eggs of 

 Tyitunis viridescens^^ were more successful than the application of 

 colchicine to these animals. The procedures with colchicine were not 

 efficient, at least when compared with treatment of plants; much was 

 to be desired for work with animals. 



Newly fertilized eggs of rabbits were treated with weak solutions 

 of colchicine. "^^ Other animals, frogs, ^^- -^"^ Triturus/'* Triton,'^ Xeno- 

 pns,^'^ Artemia^ silkworm,'*'* Habrobracon.^-^ Drosophila*-- ^'^ chick- 

 ens,"*" Amoeba,^^ were tested with colchicine for polyploidy. Gen- 

 erally colchicine has failed in comparison with the induction of 

 polyploidy in plants. ^^ 



One remarkable series of experiments demonstrated in Amoeba 

 sphaeronucleus how polyploid imicellulars could be created by colchi- 

 cine.-'^ This had no effect iniless injected into the cytoplasm at meta- 

 phase, with a micropipette. Actual counting of chromosomes was not 

 possible but there resulted larger cells with a larger nucleus. These, 

 however, at each division built one normal and one abnormal nucleus, 

 a fact suggesting triploidy. Supposedly polyploid nuclei were trans- 

 planted into enucleated fragments of normal amoebae and vice versa. 

 It was observed that the size of the tniicellidar was directly related to 

 the size of nucleus. The opposite was also true, and a normal nucleus 

 grafted in a "polyploid" cytoplasm was observed to swell considerably. 

 Cytoplasm and nucleus luiderwent several divisions and then re- 

 covered their normal volume of the original species. If the normal 

 nucleus was grafted into a fragment of a polyploid cell, growth was 

 resumed normally. These experiments have been illustrated by a 

 remarkable series of cinemicrographic documents. They have pro- 

 vided new insight on nuclcar-cytoplasmic relatiouship and the 

 possibility of observing colchicine effects in cells, the membranes 

 of which are impermeable to the drtig. 



