Cellular Growth 109 



lube widths.'-' Five-and-oiie-half-hour (ultures at 2o°i'.. luul tiil)es 

 with a :^() i)er cent increase in width over the control. Xo such sig- 

 nificant differences in witUli were found at 20°C. or 30°C. Although 

 the mean ttibe length ^vas less than control for all temperatme levels, 

 onlv at the optinunn, 25°C., was maximinii width obtained.'-' The 

 concentration of drug, 0.01 per cent, remained the same for all tests. 

 No similar increase in width was found upon adding 3-indoleacetic 

 acid, vitamin B,, or NAA to the culturing medium. 



Pollen from ColcJiicuin aiitiiiiiDdle L. was tested for response to 

 colchicine. Germination was depressed by concentrations ranging 

 from 1 .0 to 0. 1 per cent."" Tumors were observed comparable to those 

 in jjollen samples from species not known to jnoduce colchicine, and 

 thus a resistance such as was shown to c-mitosis and c-tumor has nor 

 been demonstrated for the case of the pollen tube tumors. The re- 

 sponse from these tests is of further interest in light of the report that 

 bees carrving pollen from flowers of Colchicum yield honey that is 

 poisonous due to a high colchicine content.'^" From this indirect 

 evidence it woidd thus seem that the pollen contains the drug. The 

 quantities of colchicine \\hi(h are tarried in tlie flowers are descril)ed 

 in Chapter 5. 



Epidermal jnotuberances on roots, the root hairs, involve no mi- 

 totic stages. s** These cells are suitable for testing the action of colchi- 

 cine upon enlargement of root hairs. Eight species of plants were 

 included in a study to measure differences in root hair develoj^ntent 

 between control and treated cases. ■''•'' 



Bulbous tips appeared in contrast to the normal long, thin (da- 

 mentous root hairs. The polyploid condition is not involved since 

 the nucleus does not divide. Here again is evidence for an inde- 

 pendence between the c-tumor and c-mitosis. Sometimes the end of 

 a particular hair becomes forked. -^-^ 



Other plant parts, the stem, leaf, and flowers, have hairlike cells. 

 For Helianthus, a protuberance quite different from the normal is 

 produced following treatment with colchicine."' 



Staminal hair cells of Rhoeo discolor form a chain of cells like 

 beads.-" Colchicine causes the distal cell to enlarge considerablv be- 

 yond the normal size. Each cell successively from the tij:) to base is 

 enlarged, but the size decreases progressively from the tip to the basal 

 cell. The largest cell, an end cell, is also the youngest. Maxinuun 

 increase is then projjortional to the age of the cell; yoiuiger cells ex- 

 pand more than older ones.^^* 



The stylar portion of a jnstil is elongate and is composed of elon- 

 gated cells. Flowers of Tradcscdntid treated with colchicine before the 

 pistil develops, show modification of these fforal parts.^^** Short, 

 stubbv prstillate siructmes rejilace the long filamentous styles. The 

 ntunber of cells does not change, but the manner in which elongation 



