5 



"Those peculiar and special displays of bright tints distrib- 

 uted in spots and streaks in certain and definite places only, 

 have been called 'guides' and 'path- finders,' as they invar i- 

 ahly lead to the nectaries." 



In this statement. Prof. Henslow falls into the same error 

 as several other writers, the fallacy of which is pointed out 

 on pp. 67, 70, and 74 of \wy Observations. 



Joseph Y. Bergen in Tlie American Nalnralist for No- 

 veml)er, 1.S9U, referring to the comparison of the effects of 

 mechanical irritation on animal and vegetable tissues on 

 p. 58 of my Observations on the Colors of Floiners, viz. : 

 that the bees stinudated the flower to send more pigment to 

 the honey guide, as friction or a pinch would bring more 

 blood to the cheek, observes as follows : 



"Even the lay reader will find little difficulty in judging 

 of the value of the analogy between the development of 

 pigment in cells of petals and the response of human arte- 

 ries to stimulation transmitted from the central nervous 

 system." 



My statement is perfectly plain, viz., that the additional 

 pigment which made more depth of color in the flower 

 mentioned was sent to that point the same as the blood was 

 brought. But the critic has the faculty of wresting the 

 language of the text to suit his own ideas, as is seen in his 

 accompanying conniient. It seems inexcusable that he 

 should represent me as saying that the pigment was devel- 

 oped in the cells when I distinctly say that the pigment was 

 sent to the cells. Furthermore the introduction of the sub- 

 ject of the Central Nervous System was purely gratuitous, 

 as was the absurd analogy which he himself invents, and 

 upon which he asks judgment. 



The cause of the redness of the skin from friction is 

 solely the relaxation of the coats of the blood-vessels, 

 allowing the ordinary flow of' blood to dilate them. 



We apprehend that the cause of more color in the honey 

 ouide, to which reference was made, was that the irritation 



