86 



CHAPTER OF VARIETIES. 



Gnats, however intricate, involved, or mazy their movements be, 

 cannot (any three of them) place themselves so that lines joining their 

 points of position shall form either more or less than two right angles. 



In the annexed figure suppose three gnats to be at the points 

 a b c; the lines joining these form a triangle whose three angles are 

 together equal to two right angles. Suppose they have moved to the 

 points a' b' c' ; the dotted lines joining these form a triangle whose 

 three angles are together equal to two right angles ; and in the third 

 position, a " b " c the lines joining these form a triangle having the 

 same properties. In the same manner, were they to continue to move 

 for ever, at no time would they be found in positions which, if joined 

 by lines, would form less or more than two right angles. — John Sharp, 

 Drummond Crescent. 



APPLE COCCUS. 



A. Apple covered with the Insect. B. View of the back of the Insect : 

 C. View of the under part : showing the Eggs. 



magnified. 



Scale insects (Cocci) on an apple. — I have been indebted 

 to the kind attention of Mr. Maund, the editor of the justly-appre- 

 ciated " Botanic Garden, " for a specimen of an apple, figured above, 



