FLOWERS OF IMP A TIENS FULVA 177 



Technique 



The method of handling experimental materials was described above 

 in reporting the experiments. For histological work, material was 

 fixed in chrom-acetic, Flemming's solution, and Davis's modification 

 of Renner's solution. The latter solution consists of: — 



90% alcohol 300 cc 



distilled water 200 cc 



nitric acid 10 cc 



bichloride of mercury to saturation 



glacial acetic 5 cc 



This gives a 60% solution which for use is diluted to 40% by the addi- 

 tion of water. The material is left in the solution from five to seven 

 hours. For embr)'o-sac and other delicate structures, the shorter time 

 is best. For embryo-sac and earlier stages of pollen development, this 

 solution proved superior to chromacetic, and for the histology of the 

 structures quite as good as the expensive Flemming solution. The 

 material was stained in Haidenhain's iron-alum haematoxylin, and in 

 safranin and gentian violet combination. Counterstaining the iron- 

 alum-haematoxylin with safranin or orange G proved advantageous 

 in some cases. 



IX. Summary 



I. Plants of the species at maturity vary in height from eight 

 inches to seven feet. Adverse conditions of dryness or toxicity of soil 

 bring about dwarfing. Optimum conditions for growth are abundant 

 water with good drainage and light shade or sun. 



II. Chasmogamous flowers appear in late June and last till early 

 October. 



III. Cleistogamous flowers appear in early June and last through 

 the summer. They are most abundant before the chasmogamous flowers 

 appear. They are to be found throughout the summer on plants under 

 adverse conditions, and on the lower, short side branches of many 

 plants under good conditions. 



IV. Pseudocleistogamous flowers are morphologically chasmogamous 

 buds which are self-fertilized at various stages, from the size of 

 four millimeters to a mature flower about to open. 



V. Humming-birds and bees are the agents of pollination. The 

 pollen is shed upon the bee as the insect forces its way to the nectary. 

 Later the whorl of stamens falls away and the stigma is exposed. 



