156 CARROLL— ON DEVELOPMENT OF 



with a sparse production of cleistogamous flowers. No chasmogamous 

 flowers were produced. The plants in the soil were somewhat healthier 

 probably because of the greater retention of moisture by the earth. 

 To determine the effect of high temperature, two pots were kept in a 

 ■greenhouse with temperature 15° F. higher than outside. One plant 

 ■succumbed very quickly, the other lived twenty- two days in the house 

 •and produced three cleistogamous flowers. To determine the effect 

 ■of shade, two pots were placed in dense shade, where they continued in 

 good health for six weeks producing cleistogamous flowers continuously. 

 To test the effect of soil nutrition, two pots in white sand were watered 

 with Pfeffer's nutrient solution, two in white sand received only pure 

 water and two in soil served as controls. One of the pots in soil pro- 

 duced chasmogamous flowers; all the others produced only cleistogamous 

 flowers. To determine the effect of reduced leafage, plants in the 

 woods from which the potted plants had been taken, were stripped of 

 all except two or three leaves. Two died early, three continued to 

 produce occasional cleistogamous but no chasmogamous flowers. The 

 controls in the woods produced abundant cleistogamous flowers during 

 June and July. During July, they produced chasmogamous flowers 

 rather sparingly. A dry spell in August killed practically all of the 

 plants. 



The results of experiments are in accord with the facts ascertained 

 by field observation. Cleistogamous flowers are generally produced 

 in the early moister part of the season on the majority of plants, even 

 those living under optimum conditions. They may continue under 

 even optimum conditions through the season along with chasmogamous 

 flowers. Adverse conditions of drought or nutrition, directly through 

 failure of necessary elements, or indirectly through lighting, or through 

 reduction of leafage by mechanical agents, or the attack of parasites, 

 or toxic conditions of soil, may lead to the suppression of the chas- 

 mogamous flowers. The cleistogamous flowers will then continue, or 

 will increase in numbers. 



III. General Organogeny of the chasmogamous Flower 



The development of the flower of Impaticns pallida has been de- 

 scribed by Miss Riatt (39). Her account differs somewhat from the con- 

 ditions in fulva. In the early stages the conditions are the same in both 

 cleistogamous and chasmogamous flowers. Miss Riatt states that the 

 development of the flower begins with the appearance of the saccate 

 .sepal. This is not the case with Impatiens fulva. The first member 



