1911] GATES—CHROMOSOME REDUCTION 331 
Others, for example OvERTON (17), have suggested that even 
though there is no exchange of bodies between the paired threads 
of the presynapsis, yet the purpose of this pairing may be to 
bring the threads within each other’s “influence.” A little re- 
flection, I think, will show the futility of this idea. In Oenothera 
the nuclei of the pollen mother cells have an average diameter of 
less than tow. The diameter of the presynaptic threads may be 
taken to be not more than 0.27. Supposing the presynaptic 
threads to come to lie within their own, diameter of each other, it 
is not clear what chemical or other “influence” could be exerted 
at the latter distance, which could not be exerted at the former. 
When it is considered that the chromosomes of the synaptic nuclei 
have, in higher plants, gone through hundreds of thousands of 
divisions since they were first associated at the time of fertiliza- 
tion, and that between every two divisions were periods in which 
the chromosomes were in the alveolated and distributed condition 
of the “resting” nucleus, in which the portions of the reticulum 
representing each chromosome must come into the most intimate 
Contact, at least at their boundaries; and when it is further con- 
sidered that during all this time active metabolic interchanges 
between nucleus and cytoplasm are taking place, the idea that a 
pairing of chromosomes or threads at synapsis is necessary for an 
exchange of influences loses its force. 
This leads to another series of facts which students of reduction 
have frequently failed to take sufficiently into account, namely, 
that in somatic mitoses the homologous chromosomes are in pairs. 
Montcomery ( 15) first suggested, in 1901, that in reduction homol- 
gous chromosomes of maternal and paternal origin pair. In the 
ollowing year Surron (26) showed that in Brachystola magna, 
in which various shapes of chromosomes occur, those of like shape 
are paired in the spermatocytes. The same thing has since been 
Shown for many other animals, and also for various plants. In 
1905 STRASBURGER (24) found that this paired condition is not 
confined to the heterotypic or synaptic chromosomes, but occurs 
also in the somatic tissues. This was shown by studies of Gal- 
lonia and Funkia, in which the chromosomes are heteromorphic, 
