1907.] PUBLIC DOCUMENT- -No. 73. 163 



bers for an exhaustive study into the chemical nature of the irritating 

 substance, a preliminary analysis of the material at hand was kindly 

 undertaken by Dr. Carl D. Alsburg of the department of biochemistry, 

 Harvard Medical School. His notes are as follows : - 



An extract of all the hairs furnished me was made in distilled water at 

 60 C. It was faintly clouded and slightly tinged brown. It gave no Millon 

 or Biuret reaction, and could not, therefore, have contained any appreciable 

 quantity of proteid. It showed no coagulation on heating. Its reaction was 

 slightly acid. With saturated aqueous picric acid it gave a fine, not very 

 abundant granular precipitate. With a 25 per cent, solution of phospho- 

 tungstic acid in 5 per cent, sulphuric acid there was an abundant heavy 

 precipitate, which formed gradually. With tannic acid there was an abun- 

 dant brown flocculent precipitate. Silver nitrate caused a slight brown pre- 

 cipitate. Potassium mercuric iodide, barium chloride and mercuric chloride 

 merely produced turbidity. The solution did not reduce Fehling's solution 

 either before or after boiling with dilute mineral acid. As the quantity of 

 material used in the last two tests was very small, the results must be taken 

 as provisional. The small quantity of material available, moreover, made 

 it impossible to test the toxic action of the precipitates formed by the vari- 

 ous reagents. There is, therefore, no guarantee that the substance or sub- 

 stances precipitated by phosphotungstic acid, etc., actually are the active 

 principle. 



The difficulties in the isolation of a chemical substance of this nature 

 are great, and this undertaking has been deferred until another season, 

 when it may be possible to obtain material in sufficient amount with 

 which to work advantageously. In making extracts from the nettling 

 hairs, other substances besides the irritating principle will probably be 

 found, which will have to be eliminated. In this instance the biological 

 test will undoubtedly be of value. 



The possibility of the occurrence within the body of the caterpillar 

 of an irritating substance identical with that found in the nettling hairs 

 has been considered. If a brown-tail caterpillar be laid open, and 

 precautions are taken not to introduce any nettling hairs into its tissue, 

 its fluids will be found to be highly poisonous if placed on a slight 

 excoriation of the skin. The part commences to itch at once, and the 

 skin becomes elevated, white and edematous, and a large wheal develops. 

 The lesion has a well-defined, abrupt edge, and spreads for a radius of 

 one centimeter or more about the scratch. A reddish petechial flush 

 appears over a wide area of skin about the wheal. At one-half or three- 

 quarters of an hour after the inoculation the process is at its height, 

 and after an hour the border of the lesion is not so sharply defined. 

 The edema subsides gradually, giving place to diffuse redness, and the 

 skin over this area feels slightly sore for several hours. In this manner 

 the fluids of the caterpillar may be demonstrated to be poisonous, but the 

 irritation is due to a substance quite different from that found in 



