232 PROFESSOR ALEXANDER DICKSON ON THE EMBRYOGENY OF 
APPENDIX. 
On the occurrence of supernumerary receptacular spurs in Tropzeolum speciosum. 
As may be expected, when a large number of specimens pass through one’s 
hands a good many flowers have been met with more or less abnormal in char- 
acter. I shall, however, confine myself to the consideration of those exhibiting 
supernumerary spurs. 
In the year 1866 I published a note in the Transactions of the Botanical 
Society of Edinburgh, on four cases of this abnormality observed in 7. majus. 
In these cases there was a supernumerary spur similar to the normal posterior 
one, but somewhat smaller, and placed in a line between the bases of a lateral 
and one of the anterior sepals, sometimes on one side of the flower, sometimes 
on the other. I commented upon the position of the supernumerary spur, as if 
it were there to show its want of connection with any sepal.* 
In 7. speciosum I have met with seven flowers exhibiting supernumerary 
spurs. Of these (Plate XVI. fig. 25) one (A) is essentially similar to those above 
described in 7. majus; the additional spur having a general resemblance to the 
normal one, but being somewhat smaller, and occupying a position in line with 
the interval between the left anterior and lateral sepals. In the normal posterior 
spur (xv) we have apparently six nerves; these, however, are in reality only three 
in number, which run down the inner aspect of the spur to its extremity, and 
then turn, running wp its outer aspect to the base of the calyx. Of these three 
nerves one is in line with the posterior sepal; the other two with the intervals 
between the posteral sepal and the lateral ones on either side. In the super- 
numerary spur (vy) we have but one nerve running down its inner and wp its 
outer aspect to the base of the calyx, in line with the interval between the left 
anterior and lateral sepals.t 
In the other six cases we have the very striking and bizarre peculiarity of the 
supernumerary spurs, after projecting externally to a variable but always slight 
extent, becoming invaginated or introverted like the foot of a stocking. The 
result of this introversion is that the spur makes its appearanee turned inside 
out, as a more or less elongated, curved, horn-like process projecting from the 
interior of the flower within the corolla; these supernumerary spurs being, like 
the normal one, pouch-like dilatations of the receptacle between the insertion 
of the petals and that of the stamens. Of these six cases, three present a single 
introverted spur in line with the interval between the left anterior and lateral 
sepals, as in that figured in Plate XVI. fig. 25,C. In a fourth (Plate XVI. fig. 
25, B), there are two supernumerary spurs similarly introverted, a right antero- 
* Trans. Bot. Soc, Edin. vol. ix. p. 54, referred to in Masters’ “ Teratology,” pp. 232-3. 
+ The same description applies to the arrangement of the vascular bundles in the above-mentioned 
abnormal flowers of 7. majus. 
