144 THE AMERICAN MONTHLY [Aug 



characteristic forms of the reg-ion — Arachnoidiscus ehren- 

 bergii, Isthmia nervosa, Hyalodiscus subtilis and Rhab- 

 donema crozieri. C. S. Boyer is studying- them. 



Irridescence of ^A^ater-proof Cloth. — An American man- 

 ufacturer anxious to imitate the Eng-lish g-oods spent 

 much money to discover the secret preparation. Georg-e 

 E. Fell dissected a piece under the microscope and dis- 

 covered starch granules with polarized lig-ht. Comparing- 

 with various kinds of starch, he found it to be potato 

 starch. This information could probably have been sold 

 for S500 or $1,000 if Mr. Fell had demanded it. 



Larva of Dermestes. — In drugstores, they burrow into 

 all kinds of roots and even sticks of extract of liquorice. 

 Their appetite for paint brushes results in their eating up 

 the bristles. Druggists fumigate with benzine or with 

 bisulphide of carbon. An ounce bottle half filled and set 

 in their way uncoi-ked, will kill all that are near. They 

 make pretty microscopic objects. 



The Hermit Crab's Cutting-hairs.— F. S. Morton kept 

 several hermit crabs in an aquarium and observed their 

 habits. When a bit of food touched their antennae, they 

 grabbed it and rolled it about with their foot-jaws by a 

 sawing and crushing motion before crowding the food into 

 the mouth. A microscopic study revealed the cause of 

 the motion. The crab was simply cutting up his food 

 preparatory to swallowing it. With a one-fifth inch objec- 

 tive can be seen double rows of very sharp teeth on each 

 hair. AVhen jammed rapidly into a bit of soft food, they 

 quickly reduce it to pulp. The crab lives on decayed 

 matter which these cutting hairs readily prepare, but 

 more solid food would undoubtedly break them. 



Bed Bug Hairs. — A careful examination of the body of 

 Cimex.with a good ^^th objective will show it supplied 

 with hairs which are trifid at the ends. The shaft is cov- 

 ered wdth delicate spines, long, pointing from base to tip, 

 and lying at a very low- angle in relation to the axis of the 

 shaft. He has been flattened dorso-ventrally by crawling 



