OF WASHINGTON. 289 



In all full-blown flowers at least two or three specimens were 

 found attached, and often as high as ten or a dozen. Careful 

 study of a large number showed that only small Diptera were 

 caught, and these apparently all belonging to one species. 



Aside from the mere fact of the capture of these small insects, 

 it becomes interesting to know for what purpose. Being on the 

 stigma, with no receptacle underneath, and indeed upon an organ 

 which soon had performed its function and fallen away with the 

 flower, it was quite evident that they were not caught for food. 

 Furthermore, the examination of some dried and wilted flowers 

 led to the fact that the bodies of the Diptera were yet intact, and 

 so far as could be determined had not been affected by any di 

 gestive process. The study of fresh specimens of flowers led to 

 the fact that the exudate on the stigma was abundant and gummy 

 enough to hold fast the insects, and death doubtless came to them 

 as a result of exhaustion from constant efforts to get away. This 

 raises the question whether the irritation of the stigmatical struc 

 ture through the struggling of the insect increases the amount of 

 the exudate. If so, the chances for fertilization are doubtless in 

 creased. 



In 1873, while in Louisiana, Mr. Parey made somewhat simi 

 lar observations upon this primrose, but none are more complete 

 than those of an European observer, Prof. L. Graber, recorded 

 in Entomol. Nachr. XIV, 1888, No. 4, p. 53, and also of Wol- 

 fensberger in Mittheil. Schweiz. Ent. Ges. VII, No. i, 1884, p. 

 5. Neither notes the capture of Diptera, both having observed 

 small noctuid moths sipping of the sweets and being unable to 

 again get away. The moths were found to have inserted their 

 proboscis down to the exudate-producing glands. The opening 

 to these being rather small, they were unable to withdraw their 

 tongues and fly away. Prof. Graber made a careful study of the 

 structure and anatomy of the essential organs of the flower and 

 the passages through which their tongues passed, but found no 

 provision of any kind which could be considered as having the 

 function of holding fast the insect. He concludes, quite justly, 

 that they are not caught for food, and indeed perhaps quite unin 

 tentionally. The capture seems to be due to the peculiar and special 

 desire for it which the exudate, when sipped, develops for itself, 

 inducing the moth to force in its proboscis beyond redemption. 

 In other words, the unfortunate insects seem to become victims of 

 their appetites and greed rather than from any intentional design 

 of a vegetal nature. 



From the foregoing it will be noted that this primrose cannot 

 be considered insectivorous in the common acceptance of that 

 term, namely, for food. On the other hand, Prof. Graber found 

 that when the moths were freed by being pulled away from the 

 flower they at once resumed flight without apparent difficulty. 



