270 BULLETIN UNU'WRSITY OF MONTANA 



abound. On inspecting a number of blossoms of Mimmulius (Sp — ) (B^g. 

 28) I found the styles different in various plants of all ages and proceeded 

 to tickle them with a straw. The style divides into two flat surfaces at 

 the end which spread widely apart, as is so often the case. Selecting one 

 that was well open. I found on touching it that it closed slowly and in 

 perhaps thirty seconds was shut up as tightly as if it had never been, 

 opened. After a few minutes I visited the plant again and found it was 

 slowly opening. The plants taken to the laboratory for experiment did 

 not stand the trip very well, and reacted somewhat more slowly than 

 in the field. When fertilized with fresh pollen from another flower the 

 style will remain permanently closed. 



We now come to one of the most interesting arrangements in the 

 botanical world illusti-ating plant movement to uring about cross pollina- 

 tion. The sage was figured in Darwin's earliest work of this kind and 

 given to the world as a wonderful piece of floral mechanism. 



The sage flower is irregular, having one of the petals produced into 

 a landing place for flying insects (Fig. 30.) The anthers are modified 

 with a peculiar arrangement which can be better understood from the 

 figure or the section of the flower. Two standards carry each a sort of 

 C shaped piece, which is delicately poised so as to stand in a nearly ver- 

 tical position, if the flower is held horizontally . A bee in order to enter 

 the flower must go between these standards and in so doing will neces- 

 sarily push the lower part with his head and rock the anther bearing part 

 over so as to dust his back with the powdery pollen. Since the sage 

 is proterandrous, the stigma will be non-receptive even if it were far 

 enough out to receive the pollen. If the next sage visited has a ripened 

 stigma the style bearing it will have grown long enough and will curve 

 down so that it must rub the back which was lately dusted with pollen. 

 The bee will receive no pollen from such a blossom as its pollen has all 

 been scattered. The sage has indeed a wonderful story to tell to those who 

 will stop to consider it. 



Certain flowers greet the entering insect with a bombardment of 

 pollen. This is produced in various ways and does not seem to be any- 

 thing of a surprise to the visitor who proceeds to collect his fee for carry- 

 ing his load of pollen to the next flower. 



Our common Milkweeds have a waxy pollen mass and will need in- 

 vestigation. They have been charged with the murder of hundreds of 

 innocent guests and any summer day one may find them holding their 

 dead victims fast by the legs. The insect finds himself caught and is 

 perhaps, unable to pull his legs out of the trap or pull the trap with him. 

 This trap, which consists of two bags of pollen, he is supposed to take 

 with him. An insect's foot, coming into contact with the V shaped slit 

 in the trap formed by the union of the two pollen bags, is quite likely to 

 be caught. If the pollen be ripe, and normal in every way, any ordinarily 

 strong insect is able to pull the pollen sacks free from the fiower if he 

 does not get too many feet caught at the same time. If he has a foot 

 firmly fastened in one fiower and in trying to pull out tangles another 

 foot or two, he may tire himself out and die after a hard struggle. Insects 

 usually succeed in pulling out the pollen sacks. These they carry to 

 another flower, and drag over the stigma with the desired effect. 



The orchid represents the most highly specialized flower and a con- 

 sideration of these wonderful forms must be left until another time. 



