974 The American Naturalist. [November, 
representing Spiranthes aestivalis Rich., shows, in a less crowded 
manner the sinistral anthotaxy! This specimen would doubt- 
less have sinistrorse phyllotaxy, and there should be other 
specimens with dextrorse tresses and leaf spirals. Thus it 
appears that the much-belabored phyllotaxy of the old bot- 
anists is a special case of a larger subject. 
The homodromy of phyllotaxy and antho- 
taxy within a single individual may be ob- 
served in Ænothera biennis, Verbascum thap- 
sus, Laportea and Pontederia ; and even in 
Gladiolus and Tris we may trace a corres- 
pondence between the order of equitant 
leaves and the inflorescence, Whilst the 
produce of propagation by cuttings, buds, 
and bulbs is always homodromic with the 
parent stalk, some forms, like Calla-lily, 
Iris and Rush, when growing from division 
of a root-stalk, appear to be antidromic as if 
produced from different seeds. Fig. 4 shows 
the spathes of two Calla-lilies, from the same 
root-stalk, d having the dextral margin over- 
lapping, and s having the sinistral overlap- 
ping. We may add that the akenes on the 
spadix of d make a dextrorse spiral, and 
those on that of s make a sinistrose spiral. ne a: 
ranthes aestivalis 
In this connection it is interesting to ob- Bich. he Engler and 
serve that (so far as I am able to determine Prantl. 
from leaves of Bryophyllum supplied me by 
Amherst Agricultural Station) the buds growing on opposite 
margins of the leaves are relatively antidromic. 
Secondary changes, due to twining of stems, spreading out 
of leaves under the light, opposition of leaves, and crowding of 
flowers, and perfect symmetry of seeds, often disguise the prim- 
itive character, especially in the Dicotyledones. But, even in 
these cases, we commonly find some trace remaining, In the 
great majority of plants, in fruit trees, garden flowers and 
weeds, the phyllotaxy immediately divides the representatives 
* Dextral and sinistral in this connection signify in the direction, or against the 
direction, of the thread of a common screw. 
