REPRODUCTIVE ORGANS — STYLOPHORE. 
369 
Fig. 670. — Gypsobelum or 
love-dart of Helix pomatia L., 
X 6, with an oblique section 
showing the quadruple blades 
characteristic of the Tetraspa- 
thostyla. 
The TeTRASPATHOSTYLA (rer/Das, four; (TiraOri, a blade; 5ruXos, a 
pillar) or four-bladed darts, show a great advance in complexity upon 
the dispathous form, chiefly by the forma- 
tion of two other blades at right angles to 
those already present; the four blades are 
not always e(|ually salient, as the pair repre- 
senting the blades of the Dispathostyles may 
be fully formed before the more recently 
acquired pair are beyond the rudimentary 
stage, the base is usually encircled by a 
series of regularly arranged rodlets, encirc- 
ling the basal tubercle, and the spaces 
between the blades may in certain species 
become connected together by a number of 
regularly disposed crescentic Aims. A 
tendency to the character of the Heteros- 
pathostyla is shown by the channeling of 
the outer margin of the blades, and thus forming a link with them. 
The Heterospathostyla (erepos, different; cnraOrj, a blade; stvXos, 
pillar) or variously edged dart-bearers, show the highest specializa- 
tion attained by the dart, the four-bladed 
weapon of the Tetraspathes losing their 
simple edges, each blade splitting longi- 
tudinally and being reflected outwardly, 
forming double flanges to each blade, or 
eight edges to each dart, but occasionally 
towards the free end the four primary 
blades may project beyond the point of 
reflection of the flanges, each blade thus 
showing three edges, so that a dart witli 
eight edges near the base will exhibit twelve 
towards its apex. 
These reflected flanges are the last parts 
formed, as is shown by the fact that an 
otherwise perfect dart may occasionally be 
found in which the reflected parts are still quite membranous. 
The Stylopiiore (o-tuXos, a rod ; to bear) or dart sac is an 
appendage to the female genital system, which secretes, protects, and 
protrudes the dart. It is usually a short claviform pouch opening 
11/6/1900 Y 
Fig. 680. — Gypsobelum or 
love-dart of Helix hortetisis 
Miill., X 8, with oblique section 
showing the complex structure 
of the blades distinctive of the 
Heterospathostyla. 
