70 
NOTE ON LEAF-FOLDING CATERPILLARS. 
This water will frequently make the patient sick and vomit 
whenever it meets with acids in the primae vise ; but, if continued, 
it destroys that acidity and agrees very well. 
I observ’d that, by taking this water three or four mornings 
successively, it turn’d the faeces black—a plain indication that 
iron or steel is dissolv’d in this fluid ; and, when it did not 
operate by stool, it seldom fail’d by urine. 
I cant help making one observation more, which I have long 
made and establish’d m my mind as fact, and that is that all 
mineral and medicinal waters are the most proper at the 
beginning of a disease and rather hurtful in the same disease when 
inveterate ; [also] that they are equally improper in all continual 
fevers and quotidians, inflammations of the lungs, hemorrhoids, 
hemorrhages, spitting of blood, when an ulcer is form’d in the 
lungs, and to women above three months gone with child. 
Health and Strength is above all Gold and a sound 
Body above infinite Treasure.—Eccl., 30th, 15. 23 
NOTE ON LEAF-FOLDING CATERPILLARS. 
By ERNEST LINDER, B.Sc., and CHARLES KEY. 
T HE following observations were made in 1898, during the 
course of Object Lesson Study when one of us was 
working for the King’s Scholarship. The experiments were 
original and have been never published previously. 
The larvae under observation [probably one of the .Tortricidae, 
Ed.] were found on a birch tree. In all stages of growth 
they conceal themselves from sight by rolling up a leaf of the 
tree on which they feed. The instinct appears to be a pro¬ 
tective one. 
The mechanism of the process of leaf rolling appears to be 
directly connected with the silk spinning habits of the larva ; 
no poison appears to be injected into the leaf substance, and 
if the silk threads by which the edge of the leaf is secured be 
cut, the leaf is seen to be uninjured. 
If the larva be placed on a fresh leaf, it at once proceeds to 
carry a thread across the surface of the leaf from one point to 
another ; a second thread is laid beside the first, and others 
25 This quotation is not from the Book of Ecclesiastes, as might be thought, but from the 
Apocryphal Book of Ecclesiasticus. The translation is very free and much more brief than 
later and more literal versions. 
