PREDETERMINATION OF SEX 295 



not indifferently to either pole, this would seem the more natm^al 

 designation. Without wishing, therefore, to lay too much stress 

 on the nomenclature, it seems to me that the one I have followed 

 represents more naturally the facts as described in the text. 



SEX RATIOS IN PHYLLOXERA FALLAX 



Since the galls in this species do not open to release the sexual 

 forms until a considerable number of them have hatched, and 

 since all of the inhabitants (except for rare cases) are the de- 

 scendents of a single female it is possible to get a fairly good 

 sample of the output of each stem-mother. In order to antici- 

 pate a possible objection, viz., that two or more stem-mothers 

 might be included within the same gall, I opened a number of 

 very young galls and found, with the rarest exceptions, that each 

 gall is the result of the activity of a single female. We are safe 

 in concluding, therefore, that the contents of each gall is the pro- 

 duct of a single stem-mother. But whether her daughters, the 

 apterous 'migrants,' are individually small-egg-producers or large- 

 egg-producers can not be determined; because, in this species, 

 the apterous 'migrants' deposit each egg as it matures. Since 

 eggs that are not quite mature look like small eggs they can not 

 be distinguished from them. Only by finding a gall in which a 

 single apterous 'migrant' was present that had laid both kinds 

 of eggs would it be possible to settle this question. I have al- 

 ready reported that occasionally the migrants are winged, and 

 that when this occurs each individual contains eggs that were 

 all of one sort, namely, small eggs in this instance, but this does 

 not settle the other question, however probable it may appear, 

 that each individual of this generation produces only one sort 

 of egg. 



In the following table the counts from 26 galls (July 11) are 

 given. Those with the same letter come from the same leaf. 

 The galls were old and ready to open. The old apterous 'mi- 

 grants' were still present, but empty, as though they had about 

 finished their productive life. There were present as many eggs 

 unhatched as hatched; only the latter appear in the record, or 



