PREDETERMINATION OF SEX 287 



on the under surface of the leaves of the hickory where they 

 hatch within a few days. From the large eggs emerge sexual 

 females, each of which carries a single egg. From the small eggs, 

 males emerge that are sexually mature at birth. Copulation 

 ensues; the sexual eggs are laid on the stem of the tree. From 

 these fertilized eggs the stem-mother hatches in the following 

 spring. 



The life cycle of P. fallax is as follows: As soon as the stem- 

 mother is mature she begins to deposit her eggs within the gall. 

 These eggs give rise in this species to wingless daughters (a few 

 winged daughters are also sometimes produced). Whether the 

 daughters in a particular gall are of two kinds, i.e., some contain- 

 ing only large eggs and others only small eggs, is not known, l3ut 

 both kinds of eggs are found in each gall. The large eggs, laid 

 within the gall, give rise to sexual females. The small eggs, also 

 laid within the gall, produce males. The sexual forms that hatch 

 from the eggs crawl out of the gall (whether before or after mating 

 is not known), and the single sexual egg that each female carries 

 is deposited on the tree. 



THE STEM-MOTHER'S EGGS 



As soon as the galls on the young leaves begin to enlarge in 

 the early spring the stem-mother, one in each gall, begins to lay 

 her eggs. If the eggs and embryos contained in the gall are col- 

 lected and preserved, there is a chance that the last laid egg may 

 be forming its polar ])ody and there is the further possibility that 

 one or more of these may be caught in the anaphase. A very 

 large number of eggs had to be cut into sections before the de- 

 sired stages were found. One wonders in fact that any eggs are 

 actually obtained in this phase of division. In all I have records 

 of six anaphases that give the desired information. 



The initial question is whether there exists a 'lagging' chro- 

 mosome at this time that might indicate the elimination from 

 some of the eggs of a whole chromosome. A more certain de- 

 termination would be the count of the chromosomes in the two 

 anaphase plates; but only an extraordinarily favorable case 

 would allow of this being done. Moreover, several such counts 



