31 
respiration in the case of an animal. The gases exhaled and inhaled 
during the breathing process are the same in both instances. Con- 
stantly there is an aborptiou of oXygen and a disengagement of car- 
bonic acid gas. The elimination of oxygen by the green parts of plants 
is, as before stated, not so much an act of respiration as of digestion. 
The plant is thus constantly exposed to two antagonistic forces — the 
one tending to build up, the other to destroy, the organism. At cer- 
tain epochs in certain organs, and if kept in darkness, the plant 
invariably emits the same gases as an animal does. So also, under the 
influence of green light, the ordinary action of leaves is partially 
inverted. In alluding to the effect of light on the disengagement of 
o c* o o 
oxygen gas, it should, however, be remembered that the light can be 
and is fixed or stored in the plant, so as to operate for a time even in 
complete darkness.” 
In the few following pages are given the characters of the seven 
natural orders of plants with which teachers who purpose taking 
botany as one of the subjects at their final examination are to become 
acquainted. Here they will And not only the characters of the order 
as a whole, but of each suborder and tribe, with also the name of some 
easily obtainable typical plant of each tribe. To fui’ther show plant 
classification into genera and species, the generic and specific characters 
of a plant in each order are given. This will, it is hoped, be acceptable 
to the majority of persons, whether taken advantage of by teachers 
or not.^ 
Order LEGUMINOS^E. 
Amongst Dicotjdedons this oi’der stands second in point of 
numbers. It contains about 7,000 species in 400 genera, and the 
species are met with in every part of the globe. 
Plowers, irregular, usually hermaphrodite ; regular, usually 
polyg<nmous. Ivnown species over 6,500. IN ext to Compositje, this 
is the largest natural order of phsenogamous plants. Calyx of 5 or 
rarely fewer usually united sepals, campauulate or tubular, more or 
less divided into 5 or fewer teeth or lobes, or rarely the sepals entirely 
distinct. Corolla of 5 or rarely fewer ])etals, perigynoua or rarely 
bypogynoua ; very irregular in the first suborder (PapilionacsB), less 
so in the second (Cbesalpinieae), small, regular, and the petals often 
united in the third (Mimoseae). Stamens twice the number of petals, 
rarely fewer, or sometimes indefinite, inserted with the petals. Ovary 
single (consisting of a single carpel), wdth 1, 2, or more ovules arranged 
along the inner or upper angle of the cavity; style simple. Eruit, a 
pod (legume), usually flattish, and opening round the margin in 2 
valves, but sometimes follicular or indehiscent, or variously shaped. 
Seeds with 2 large cotyledons, a short radicle, and, with few excep- 
tions, little or no albumen. The species consist of herbs, shrubs, 
trees, or climbers. Leaves alternate, or rarely opposite, usually 
furnished with stipules, compound, or reduced to a single leaflet, or 
to a dilated petiole (phyllodium), or in a few cases really simple, the 
leaflets or leaves entire or rarely toothed or lobed. Elowers in 
axillary or terminal racemes, spikes, or clusters, when terminal, often 
becoming leaf-opposed by the growth of a lateral shoot rarely solitary 
and axillary. 
* The descriptions given have particular reference to Australian plants. 
