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THE AMERICAN NATURALIST [Vol. XLII 



which determines the above-noted characteristic appear- 

 ance of the froth of the different species. The insect 

 does not always wait until the body is completely covered 

 with fluid before injecting the air into it. 



In order to make sure that the larger portion of the 

 fluid came only from the anus, the latter was closed by 

 a plug of lens paper, which being capped with balsam, 

 and then allowed to dry for a few moments, closed the 

 anal opening perfectly. The insect, upon being placed on 

 a twig, after locating a satisfactory place, soon pierced 

 the plant with its beak and began feeding. It rapidly 

 increased in size and became much distended and swollen. 

 Although observed for over three hours not a single drop 

 of fluid came out. In a specimen whose anal opening had 

 not been carefully sealed a drop of liquid succeeded in 

 coming out of the tip of the abdomen, on the side of the 

 filter plug. Thus it was demonstrated, as any one who 

 desires to repeat the operation may, that at least one of 

 the constituents of the froth is emitted from the anal 

 opening, and that the views of Mouffet, Porta, Berlese 

 and Girault are not correct, for according to their inter- 

 pretations the closing of the anus would not interfere 

 with the production of the froth. 



Histological Study of the Structures of the Glands 

 of Batelli 



While it is seen that the greater portion of the liquid 

 from which the froth is produced is derived from the anus, 

 there arises the question whether there are not other or- 

 gans, the secretion of which may take a prominent part 

 in the formation of the spittle. 



In the pleural region of the seventh and eighth abdom- 

 inal somites very large hypodermal glands are located. 

 To the naked eye these glands are not easily discernible 

 upon the nymph, their positions being detected only if 

 there happens to be a large supply of their secretion. 

 Under the hand lens when the abdomen is extended, there 

 are to be noticed whitish patches, even when the secretion 



