NATURE OF POLYHEDRAL BODIES FOUND IN INSECTS. 377 



were then applied and we obtained positive reactions with xantho- 

 proteic, Millon's, biuret, Adamkiewicz's and Lieberman's tests. 

 It was next found necessary to obtain the polyhedra in solution 

 so that the various coagulation or precipitation tests could be 

 performed. 



Before testing the solubility of the polyhedra in various re- 

 agents they were first rubbed energetically in an agate mortar 

 with the addition of a little sea sand. This grinding was found 

 necessary for the reason that the outer surface of the bodies is 

 composed of more resistant material than the underlying strata. 

 By grinding with sea sand the polyhedra are fragmented and 

 this offers more delicate surfaces to the action of the reagents. 



The polyhedra were found to be insoluble in hot or cold water, 

 alcohol, chloroform, ether, or xylol. They dissolve readily in 

 strong acids and alkalies, but these reagents were thought to 

 produce too great a hydrolytic cleavage of the protein molecule, 

 and since we did not wish to alter our material to any appreciable 

 extent a number of milder reagents were tried. Moreover, from 

 the standpoint of the classification of proteins it is important 

 to determine just what will and what will not dissolve the 

 material. 



The following solubility tests were performed. Two grams of 

 ground polyhedra were divided into four parts. To Y^ gram 

 water was added; to ^ gram .5 per cent, and to another ^ gram 

 2 per cent. NaCl solution, and to the fourth ^ gram 10 per cent. 

 Na2COa were added. The tests were kept over a water bath 

 for 133/2 hours at a temperature varying between 55 and 58 C. 

 At the end of this time the solutions were filtered and the various 

 tests for soluble proteins applied. All of the tests (acetic acid, 

 nitric acid, cupric sulphate, mercuric chloride, acetic acid with 

 potassium ferrocyanide and ammonium sulphate) were negative 

 showing that nothing went into solution. 



Two grams of polyhedral material were again divided into four 

 parts and treated respectively with H 2 O, .5 per cent, and 2 per 

 cent. NaCl and 10 per cent. Na2COs. The tests were placed 

 over a small direct flame for two hours. At the end of this time 

 the solutions were filtered and the tests for soluble proteins 

 applied. Negative tests were obtained with the water and salt 



