446 



THE GRASSERIE OF THE SILK- WORM. 



By Philip Walker. 



The prevalence of grasserie in the United States during 1890, as stated 

 in my last annual report, points to the necessity of furtlier study of the 

 disease and a search for some means for its prevention or cure : 



When the sixth edition of Dr. Riley's Manual on Silk Culture, issued 

 by the Department, was prepared, the rarity of the malady led him 

 to refer to its slight importance and the little attention heretofore 

 given it by scientists. In Europe the few worms which are attacked 

 by grasserie are hailed with delight by the raisers, who say, ^^Fas degras, 

 pas de eocons^^ (no grasserie, no cocoons). This sentiment is due to the 

 fact that grasserie is seldom accompanied by other diseases, and in 

 itself is rarely disastrous. The only precaution taken with such rare 



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Fig. 34. — Polybedral granules of the grasserie. 

 (After BoUe.) 



specimens as thus occur is to remove them from the rearing tables for 

 fear that they will soil the other worms or their cocoons. The literature 

 of the subject is therefore small. Pasteur's only reference to the malady 



