T. P. SMITH ON THE FINER STRUCTURE OF BUTTERFLY SCALES. 181 



appearance, is not unlike the hairs on the leaves of some plants. 

 The scale is somewhat rounded in section, and this internal growth 

 seems to be the means of keeping the two membranes apart. 



With regard to pigment cells, I do not think there are any, as I 

 have never been able to trace any such between the two membranes. 

 Dr. Pigott, in last Friday's " Mechanic," like Silas Wegg, " drops 

 into poetry " and says, " All pigment is pure figment," and in this I 

 agree with him. In conclusion, I beg to say that I am not wedded 

 to any opinions expressed in this paper, but am ready to change 

 them on receipt of evidence. I have not had the time to become 

 master of all the facts, and no doubt will have to modify some of 

 my opinions on further investigation. 



