( Ixxvii ) 



" This is a great contrast — really deserted desert most of it 

 without even camel thorn— and cultivation, gardens, dates, &c. ; 

 consequently no insects. Of course they may buck up in 

 autumn or spring. The laboratory is efficient : I am doing 

 flies, and have a great time running everywhere at my own 

 sweet will. 



" What strikes one here is the extraordinary comfort of life 

 compared with what it must have been. You light in at 

 some little desert post and find the fans running, and the 

 soda bubbling, and the ice-machine clanking ! " 



Salt (Chlortde of Sodium) probably sought by the 

 Hesperidae. — ^Prof. Poulton said that he had received the 

 following letter from Mr. S. A. Neave, referring to the 

 observations recorded by Mr. C. 0. Farquharson : 



"Nov. 25, 1917. 



" As regards the note about the peculiar habit of RJiopalo- 

 campta forestan, on p. Ixxx of the 1916 Proc. Ent. Soc, I 

 have seen this exactly as described both in this species, in 

 R. j^isistratiis, F., and in at least one of the common Parnaras, 

 I think P. fatuellus, Hopff. I had noted in P. Z. S., 1910, 

 p. 85,* that R. forestan was much attracted by perspiration, 

 but had not at that time seen the moisture extruded from 

 the abdomen. In my case there could have been no question 

 of ink, the back of my hand or arm being the site selected, 

 though the fluid absorbed may have been mixed with the 

 perspiration. The extruded fluid seems to be usually colour- 

 less, but in one case, I am not quite sure in which species, 

 but I think R. pisistratus, it was of a milky appearance." 



Mr. Neave had also informed Prof. Poulton that the 

 skippers would often settle upon the shirt-cuff and there act 

 as above described. Now besides water the chief constituent 

 of perspiration, and the only one likely to be of value to the 

 insect, was salt, while the observed behaviour strongly sug- 

 gested that it was some soluble substance like salt that was 

 sought. Rapid evaporation in the sun would leave salt in 

 concentrated solution or even dry on the skin or in parts of 



* " This species is much attracted by moisture, and if one is sitting or 

 standing still will often nettle on one's hands and arms attracted by 

 the perspiration." 



