42 
PACIFIC SCIENCE, Vol. IV, January, 1950 
As noted earlier, strong secondary associa- 
tion in P. suberosa (2n = 24) is taken as 
indicative of its polyploidal origin. The 3 6- 
membered form undoubtedly originated fairly 
recently as an autotriploid as shown by the 
absence of marked morphological differences 
in plant characters. It is supposed that tri- 
ploidy resulted in the species through the 
mating of an unreduced gamete with a nor- 
mal, reduced gamete. How the unreduced 
gametes might have been produced is sug- 
gested by the case of syndiploidy observed in 
an anther of P. subpeltata. 
The occasional occurrence of all degrees 
of multivalence up to and including sexi- 
valence lends credence to the supposition that 
the 2n = 24 form is itself polyploid, at least 
tetraploid if not of a higher order of poly- 
ploidy, and that the derived form is at least 
hexaploid. The presence of 6 genomes, al- 
though bringing about some slight degree of 
irregularity in meiosis, allows for more or 
less normal anaphasic separation into two 
gametic 18-chromosome complements. 
CONCLUSION 
The study has shown that the basic chro- 
mosome number for the genus is at most x = 
6, and may possibly be x — 3, rather than x 
= 9 as indicated by Darlington and Janaki 
Ammal (1945: 114). It has also called 
attention to the discrepancy in chromosome 
number determinations for P. foetida. It is 
thought by the writer that the aneuploid 
number of P. foetida presages the existence 
of another euploid series in the genus. The 
determinations made bring to 29 the number 
of species and variant forms for which 
chromosome numbers are known or may be 
assumed from the composition of various 
hybrids. 
It seems highly probable that there may 
exist chromosome numbers other than those 
reported here among the 300-odd species of 
Passiflora which have not been examined. 
Studies of a greater number of species more 
fully representing the recognized taxonomic 
groups and of additional interspecific hybrid 
material would aid considerably in determin- 
ing origins and relationships within the genus 
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