34 



Colchicine 



TABLE 2.1 



Percentage of C-mitoses for One Hundred Figures 



(After Mangenot, 1942) 



Root Tips of Germinating Onion Seedlings — Colchicine 0.05% 



Resting stage. . 



Prophase 



Meta-anaphase 

 Telophase .... 



Control 



85.0 

 6.6 

 4.2 

 3.4 



24 hi 



48 hrs. 



85.0 

 3.2 

 9.6 

 2.2 



86.2 

 2.8 



7.2 

 3.8 



72 hrs. 



90.0 

 1.6 

 6.4 

 2.0 



96 hrs. 



96.6 



0.6 



2.0 



0.8 



Onion Bulb Root Tips— Colchicine 0.05% 



Resting stage. . 



Prophase 



Meta-anaphase 

 Telophase .... 



Control 



18 hrs. 



40 hrs. 



77.30 

 7.53 



13.84 

 1.30 



93 hrs. 



88.61 

 1 .84 

 8.46 

 1.07 



Onion Bulb Root Tips— Combined Test— Heteroauxin 0.0001 %— Colchicine 0.05% 



Control 24 hrs. 



40 hrs. 



Resting stage 



Prophase 



Meta-anaphase . . . 

 Telophase 



?8.42 

 8.21 

 1.58 

 1.78 



80.5 

 4.6 



13.10 

 1.80 



84 . 50 

 4.50 

 8.00 

 3.00 



67 hrs. 



89.20 

 2.60 

 5.30 

 1.90 



91 hrs. 



90.70 

 1.50 

 4.80 

 3.00 



139 hrs. 

 97.30 



0.4 

 1 .40 

 0.90 



A similar inhibition was seen in neuroblastic cells'^-* but expressed in 

 somewhat ditterent manner. Cells subjected to colchicine in late pro- 

 phase remained arrested in jjrophase for 150 miniues before develop- 

 ing a meta])hase stage. ■^" This process at late pro]:)hase, a transition 

 from projjhase to metaphase, requires 32 minutes.-^"' 



Critical time-dose relationships nuist be observed to produce maxi- 

 imnn arrested metaphases in regenerating liver of rat."- ^-- ^•' This 

 dose is one microgram per gram of body weight. Above this concen- 

 tration, colchicine catises reduction in the mitotic stages in metaphase. 

 Even before any supralethal dose kills the animal, the inhibiting 

 action tipon mitosis is observed. That is, the prophases do not seem 



