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THE AMERICAN NATURALIST [Vol. XLII 



and give in details the observations made to clear up the 

 confusion. 



Methods 



The methods used in the biological observations are 

 given in the body of the text. I refer here only to those 

 used for the examination of the histological structures. 



In preparing the tissues of the spittle insects for his- 

 tological examination various methods of fixing, killing 

 and staining were used. The best results were obtained 

 by killing in hot water and then transferring immediately 

 into Fleming's strong solution for twenty-four hours. 

 Tissues killed directly in hot Fleming 's fluid, while giving 

 satisfactory differentiation of organs like the testes, in- 

 testine and fat cells, gave poor results with the glands. 

 Very good results were obtained by killing in hot Gilson's 

 fluid. 



Good serial sections of the nymphs were obtained by 

 infiltrating in paraffine 54° C, while adults imbedded in 

 62° C. paraffine gave better sections. Sections were cut 

 from three to ten microns. 



Staining was done on the slide with iron hematoxylin 

 or Delafield's. Whenever the latter was used the tissues 

 were counter-stained in eosin. 



In order to get satisfactory preparations of the glands 

 in surface view the tissues were killed in hot Gilson's 

 fluid and allowed to stand for one half hour after having 

 been opened and the fat carefully removed. After wash- 

 ing in seventy per cent, alcohol and a few drops tincture 

 of iodine, the specimens were stained in borax carmine for 

 a few minutes, dehydrated, cleared and mounted in bal- 

 sam. Great care must be observed in teasing the fat 

 away from the glandular region, otherwise the cells will 

 be disarranged. 



Personal Observations upon the Production of the 

 Froth 



I first studied the gross features of the froth formation 

 in several specimens. A large specimen of Aphrophora 



