26 BOTANICAL GAZETTE [yuty 
idea of the pairing of threads in synapsis in Drosera, makes it highly 
probable, and in fact necessary, that the method of reduction in the 
Oenothera hybrid be different. This is a strong argument not 
only against pairing of maternal and paternal spirems in Oenothera, 
but in favor of the probability that reduction takes place in diverse 
ways in the two genera. A considerable amount of time has already 
been devoted to the study of reduction in this Oenothera hybrid, and 
an account will be published later. So far as observed it shows no 
differences in method from the account given here for the pure races. 
The hypothesis of the pairing of parental spirems in synapsis in 
Oenothera being thus rejected, the other alternative remains, namely, 
that the double spirem results from a split; and this appears to satisty 
all the facts. The observations have already shown that the spirem 
segments into a single chain of chromosomes. The description of 
events in Oenothera from synapsis on thus agrees in outline with the 
1904 account of STRASBURGER (30) in Galtonia, and in general also 
with that of Farmer and Moore (9) in Lilium, Osmunda, Psilotum, 
and Aneura, FARMER and SHOVE (10) in Tradescantia, and MoTTIER 
(19, 20) in Lilium, Podophyllum, and Tradescantia. The belief of 
the writer is that some of these forms will be found to correspond 
more nearly with the account which involves a pairing of threads, and 
some with the account involving only a split. 
Another important matter which requires mention at this time 
is the nature of the chromosome distribution which takes place on the 
heterotypic spindle in Oenothera. As already observed, the chromo- 
somes even during spindle formation are frequently unpaired. This 
appears to be due to the weakness of the mutual attraction which 
ordinarily leads to pairing. Granting that homologous maternal and 
paternal chromosomes unite when pairing takes place, what are the 
possibilities regarding the unpaired chromosomes? Pairing insures 
ordinarily that the members of the pair will proceed to opposite 
poles of the spindle, and hence that the homologous maternal and 
paternal elements will enter different nuclei. There is no such 
certainty in the distribution of the unpaired chromosomes, so that it 
might be expected that in certain cases both members of a pair would 
enter the same daughter nucleus. It is important to note that this 
result is entirely independent of the origin of these chromosome 
