No. 504] ORIGIN OF FROTH IN SPITTLE-INSECTS 797 



A study of longitudinal and cross sections failed to show 

 any such glands as described and figured by Porta. 

 There are to be found the prominent oenocytes which are 

 more numerous in the ventral surface of the animal. 

 Berlese (1907) dismisses this view by stating that it is 

 these oenocytes which Porta has mistaken for spittle 

 glands. While this is doubtless in part true, I believe, 

 as near as can be judged by the imperfect illustrations, 

 that Porta was also misled by oblique sections through 

 the body wall. 



Porta (1900) mentions an oval gland which he says is 

 situated in the fourth somite near the intestine, which 

 he further states is ductless and has no connection what- 

 ever with the intestine or any other organ. He thinks 

 that it may be concerned in the formation of the spittle, 

 though he gives no tangible reason in support of this 

 view. After careful study of a number of series of sec- 

 tions I failed to find any such independent gland and I 

 am convinced that he in reality had under observation 

 one of the cephalic glands and that of course it has no 

 relation to the spittle secretion. 



This same writer describes other glands which he con- 

 siders are concerned indirectly in the production of the 

 spittle. These he describes as being situated in the 

 latero-ventral region of the third, fourth, fifth and sixth 

 abdominal segments. He states that there are four pairs 

 of these glandular masses, and in these ramify numer- 

 ous tracheae. He was unable to find any external openings 

 to these glands and did not notice their connections with 

 any other organs. The fact is that they are accessory 

 reproductive organs, and that in perfect series their con- 

 nection with this system may be most readily traced. 



Summary 



The secretion of the spittle insect is made up from two 

 sources : 



The fluid portion is the anal secretion into which the 



