1967] 
Eisner j Alsop & Eisner — Defense Mechanisms 
ii5 
prevails in nature. Apheloria collected early in the season (first week 
of May) had as variable an output as those collected in midsummer 
or late November. In P seudopoly desmus , output was also broadly 
variable on the two occasions that the species was collected (May 
and October). One wonders about the meaning of this variability. 
The fact that most millipedes have a yield that is considerably below 
the maximum recorded for their species might be taken to indicate 
that their glands are in a state of partial depletion and that encounters 
with predators are commonplace throughout the season. However, 
cyanogenetic potential may also be subject to instrinsic variation, and 
a submaximal yield need not by necessity reflect a history of past 
assault. Attempts to raise Apheloria in the laboratory in order to 
determine whether in the absence of predation their cyanogenetic 
potential achieves uniformity at high levels met with failure. 
In an undisturbed millipede, there is no detectable spontaneous 
loss of hydrogen cyanide. Assays performed on groups of five milli- 
pedes, confined undisturbed in chamber A of the apparatus for up 
to two days, invariably proved negative. Thus, the valve that ordinar- 
ily seals the connection between the two compartments of each gland 
Cyanogenetic 
Organism Capacity 
MQ/9 
Prunus se rot in a 
(Wild black cherry) 
2100 
Prunus amygda/us 
(Bitter almonds) 
1800 
Trig to chin sp. 
(Arrowgrass) 
500 
Bahia oppositi folia 
(Bahia grass) 
300 
Pseudopolydesmus serratus 
280 
Apheloria corrugata 
135 
Table I. Mean cyanogenetic output of Pseudopolydesmus and Apheloria, 
compared with some of the higher cyanogenetic capacities recorded for 
plants (compiled from references in Kingsbury, 1964, and Wokes and Willi- 
mott, 1951). 
