468 
are true to their phyllotaxy. In the horizontal members even the 
ridges of cork partially conform to the phyllotaxy of the particu- 
lar member by a slight flexure to one side or the other. But the 
branches fromthe stem, or the branches from a branch do not 
necessarily conform to the phyllotaxy of the part from which they 
diverge; some of the daughter-branches may be homodromic, 
others heterodromic, as compared with the mother-branch, nor 
have I been able to discover any law in the case. 
Perhaps these instances may favor the view that what we have 
in antidromy is not so much a special kind of heredity as an im- 
pulse depending on physical or nutritional causes, giving a bias 
to the young embryo or the young bud, which when once received 
is maintained. But whatever be the explanation offered, the facts 
are too important to be overlooked. 
Sachs in his Astory of Botany treats Piylataxy as an ex- 
ploded error, and gracefully celebrates its obsequies with the part- 
ing note that though wrong, it was useful in its day, adding “ we 
would as little wish to omit it from our literature as modern as- 
tronomy would wish to see the old theory of epicycles disappear 
from its history.’ But what he and others condemned was an 
artificial or idealistic law imposed on plants in mathematical dra- 
pery; the twists that will naturally result from pressure upon 
young parts or from peculiarities of direction and of amount of 
nutriment, and from the modifying influence of light or climbing 
habits, are conceptions that were unknown to the fathers of 
mathematical phyllotaxy. From inattention to these considera- 
tions our botanists often miss what ought to be plain enough. 
Thus among the cryptogams Sachs gives us spores of Eguisefum 
with a wrong spirality for their elaters (I confess my own sin 
here). Dodel-part gives odgonium of Chara wrong twisted ; Engler 
and Prantl seem to require amendment as to Evodium (3: 4- 2) 
and as to Flalicteres (3: 6.93); and such instances may be multi- 
plied. 
Homodromic spiralism is not infrequent in phenogamic as 
well as in cryptogamic plants; as the dextrorse twining of some 
Leguminosae, of Convolvulaceae (including the Dodders) and of 
Celastrus ; and other species are sinistrorse. Whilst it was shown 
in the paper on Antidromy that the mode of bursting of the car- 
