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BULLETIN UNIVERSITY OF MONTANA 



The first (Fig. 24) shows how Sprengel taught the method of fertili- 

 zation by showing how the pollen is shed upon the stigma by being borne 

 above it. 



The second chart (Fig. 25) shows how Sprengel overcame objections 

 to his theory when his attention was called to flowers which bear the 

 anthers below the stigma. It shows bees crawling over the nectaries, In- 

 cidentally smeai'ing themselves with pollen, and then climbing over the 

 stigma, carrying the pollen with them. 



The third chart (Fig. 26) shows the next problem with which Sprengel 

 was confronted. iilowers were found where the pollen is all shed before 



Fig. 25. 



the stigma is open or receptive to pollen. These are what we now call 

 proterandrous flowers. Somewhat similar in nature is the problem of the 

 proterandrous flowers where the stigma ripens before the anther. Sprengel 

 is said to have admitted that he could not solve all these enigmas but 

 that, nevertheless, he thought there were reasons for these various struc- 

 tures. 



Darwin, coming at the problem from the standpoint of cross-fertili- 

 zation, saw it as in chart four (Fig. 27), which represents bees going from 

 the ripe anthers of one flower to the receptive stigmas of older flowers; 

 and it was made clear. 



In his twelve years of experimentation on the subject of "Self and 

 Cross Fertilization in the Vegetable Kingdom," Darwin showed that not 

 only was it advantageous for flowers to be fertilized by pollen of other 

 flowers of the same species, but that they produced more seeds if ferti- 

 lized by pollen from distant fields. These two books by Darwin are of 

 great interest to the botanist and may be read with profit by any one. 

 As examples of the exprimental method of to-day they are worthy of con- 

 sideration. I suppose no other man has sepnt such years of painstaking 

 labor and accompanied his theories with such an enormous amount of 

 data. 



Some plants, like the common violet, have two kinds of flowers. We 

 only note the ones that open to insects with their beautifully colored co- 

 rollas, but there are others, which may be found later in the summer 



