76 SIR J. LUBBOCK—PHYTOBIOLOGICAL OBSERVATIONS. 
(fig. 156). The caulicle is undeveloped, the cotyledons are oblong 
elliptic, emarginate, obtuse, generally unequal-sided or subfal- 
cate, longly petiolate, 8-nerved from the base, and finely reticu- 
late, with the lateral nerves becoming incurved and uniting with 
the midrib close to the apex, glabrous, light green above, paler 
beneath, shining on both surfaces; lamina 18-24 millim. long, 
83-11 millim. wide; petioles 60-100 millim. long, connate into 
one terete piece for 55-75 millim. of their length, split a little 
way at the base to allow the plumule to emerge, free in the upper 
part, semiterete and slightly channelled above, glabrous, shining, 
dull brownish green. 
In this case it is obvious that if the petioles had been separate, 
they would have been far too weak to stand upright, and their 
length therefore would have been comparatively useless. 
In Polygonum polystachyum, again, the petioles are connate and 
form a hollow tube through which the leaves pass; so that the 
seedling has the appearance of possessing an erect caulicle with 
nearly sessile cotyledons. 
Unequal Cotyledons. 
In my previous memoir I gave (7. c. p. 869) several cases in 
which the two cotyledons are unequal, and pointed out the rea- 
sons to which in the several instances this seemed to me to be 
Fig. 157. Fig. 158. Fig. 159. 
Fig. 157. Coreopsis Atkinsoniana : longitudinal section of achene. x 10. 
Fig. 158. Ditto: transverse section of achene. x 10. 
Fig. 159. Ditto: embryo. x 10. 
due. Coreopsis Atkinsoniana affords us a case which I then acci- 
dentally omitted. The seeds are obovate, curved longitudinally, 
and compressed dorso-ventrally, conforming to the interior of the 
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