74 
Th .n. Montgomery, jr. 
shows mavked size differeuce of its elemeiits, this is still more pro- 
noiiuced iu tlie largest pair of Corizus, and notably so in a number 
of cases of tbe diplosomes (paired modified cbromosomes) of Hemip- 
tera as described pai'ticularly by Stevens (1905), Wilson (1906), 
and me (1906). 
Tbiis constaut morpbological cbromosome differeuce is a condi- 
tion tbat must bencefortb be reckoued witli, and it speaks strougly 
for the view tbat particular cbromosomes represent partieular meta- 
bolic (pialities, tberefore particular bereditable energies. Tbis result 
from morpbological study is tbeu quite in agreement witb tbe ex- 
perimental results tbat bas beeu so excellently syntbetized by Boveki 
(1907). It is quite probable tbat it will be not possible to demou- 
strate such difference on the cbromosomes of all species, but so far 
tbe tbeory bas been tested ou ouly a few. Kow tbat attention is 
called to cbromosome difference iu tbe classical egg of Ascaris tbe 
sceptics may be led to give tbe wbole subject a reuewed examiuation. 
Literature List. 
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Bouixg, A. M. 1907. A Study of the Spermatogenesls of twenty-two Species 
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Boveri, Tu. 1888. Zellenstudien. Heft 2. Jena. 
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