92 THE FLOWERING PROCESS 



procedure we examine the buds under a binocular, dissecting micro- 

 scope (about 36 diameters magnification) 9 days after the beginning 

 of the experiment. This is quite arbitrary, but it is convenient. 



What about environmental effects upon rate of floral development ? 

 Under certain conditions such effects may be very striking. For ex- 

 ample, with an extremely low night temperature (only a few degrees 

 above freezing) and a relatively cool day temperature, no development 

 occurred at all as compared to a very rapid development when 

 temperatures were high (Fig. 5-3). Yet in practice, if conditions will 

 allow a fair development of induced control plants, the problem is 

 not a serious one. The control plants are subjected to the same 

 developmental environment as the treated plants, which is insured 

 by the way that they are placed on the greenhouse benches. Thus 

 only the treatments vary, and everything else is maintained com- 

 parable between controls and treatments. Floral Stages of treated 

 plants are not considered in an absolute sense, but only as they 

 compare with untreated controls in the same experiment. This is the 

 procedure which is commonly followed in science, and indeed it 

 might be used to study floral development itself (as in Fig. 5-3). 



It might be even better to standardize environmental conditions in 

 such a way that the flowering controls always develop to the same 

 stage in the same number of days, providing that they have been 

 given the same inductive treatment. Temperature, light conditions, 

 fertilizer and moisture could all be standardized to realize this end. 

 When this is achieved, we will logically make absolute comparisons 

 between experiments, as well as between treated and control plants 

 within an experiment. Such a condition has yet to be reached, but 

 it is being approached at present, especially in growth chamber 

 experiments. 



