784 



THE AMERICAN NATURALIST 



[Vol. XLII 



HlSTOBICAIi 



Gruner (1901) has given a very extended and excellent 

 historical account of the work of individual writers on 

 these insects. It is intended here merely to group the 

 views held by the various writers, at the same time adding 

 the opinions held by writers since the appearance of 

 Gruner 's paper. 



As far as the writer has been able to determine from 

 original sources, there are seven theories which have been 

 advanced in explanation of the production of the froth. 

 This does not take into account the belief of the southern 

 negroes, who claim that the frothy masses are caused by 

 horseflies, neither does it take into consideration the opin- 

 ion formerly held by many, that it is the product of the 

 stars, nor the view that it exudes from the ground. 



Isidorus, who lived in the sixth century, is cited by 

 Gruner as the first to write on this subject. He believed 

 that the froth was the spittle of the cuckoo bird, and that 

 from this secretion the cercopid spontaneously generated. 

 Mouffet (1634) and other writers came to the same con- 

 clusion respecting the origin of the spittle and insect. 

 Aldrovandi (1610), in his Ornithologia, strongly denies 

 this assertion, but fails to enlighten the reader as to the 

 true solution of the problem. 



According to Gruner 's account, Bock (1546) appar- 

 ently believed that the froth was the product of plants 

 and he gave a list of the plants producing it. 



John Ray (1710) states that the spittle mass was 

 caused by the insect found within the mass, and believed 

 that it was expelled from the animal's beak. He was 

 upheld in this view even in recent times by as prominent 

 an authority as Uhler (1884). Fabre (1900) states that 

 a clear fluid comes out of the beak and that to this fluid 

 the insect injects air bubbles by grasping air with the 

 last pair of lateral prolongations of the ninth abdominal 

 segments. 



Blankaart (1688) believed that the froth came out of the 

 anal opening of the insect. In this view he is supported 



