* 
CAMBIUM AND MERISTEM. | 13 
these are Genista, Galium, Prunus oe Symphytum officinale, 
Mercurialis perennis, Trifolium medium, Solanum Dulcamara, Helilotus, 
Cynoglossum officinale, Lotus and other Zabechinbads, Lamium album, 
ne Mentha, Marrubium vulgare, Nepeta Cataria, Ballota nigra, 
with many nocturnal Lepidoptera, and this, perhaps, partly accounts 
for the great number of individuals of this plant. Moths usually 
abound in places where the Zeuerium grow 
y flower-frequenting stat moths have more or less strongly 
developed crests of hairs on the thorax. Many flowers frequented by 
these moths have blossoms with mouths directed to the horizon (¢.6., 
neither drooping nor facing the zenith), and stamens more or less 
exserted and ascending; styles also more or less exserted. 
moth visits such a flower it either hovers in front of it and plunges its 
haustellum into the corolla, or else rests on the flower and does th 
same. In either case it brushes the stamens with its thorax, aed 
carries off eo a supply of pollen to the next flower visited. 
Now, it is worth noting that some of the moths which hover (e.g., the 
Plusvide* and Cucullia) have very strongly developed thoracic crests, 
long exserted ascending stamens and styles (¢.g. Echium vulgare and 
Lonicera Periclymenum). If ens in th ts were short, 
the*pollen would have little chance of being ed off by the thorax 
f the moth, and it does not rea dhere (as the sticky pollen masses 
of the orchids do) to the haustellum, and if rax of the moth was 
smooth the pollen w not be off, ev 
though the stamens are exse ; whereas with exserted and ascend- 
ing stamens in the flower and crested thorax in the moth, we have 
every condition necessary to insure a greater or less quantity of pollen 
ares conveyed from one plant to another. In the Ladiate the stamens, 
ough so few, seem to be especially arranged in many species, that 
panty chance may be afforded of pollen being carried. In Ajuga reptans 
and Zeucrium Scorodonia the stamens are exse and ascending, an 
are four in number—two long and two shorter. An insect therefore 
in plunging its head into the corolla would almost necessarily brush 
all the four stamens. These plants are much visited by moths. 
CAMBIUM AND MERISTEM. 
By W. R. McNas, M.D., 
Professor of Botany, Royal College of Science for et pen 
In considering the structure of stems, it is of primary importance 
to have definite ideas regarding the tissue which increases by division 
of its cells, and thus adds to the bulk of the whole. Much hay 
* Have also crested heads. 
