THE ORANGE COCCUS. 3 
differs from the Saxifragacee by possessing them, while their 
absence distinguishes AZontinia from the Onagracee. ‘The other 
crystals may occur free in the cavities of plant cells, as is the case 
with many found in Gesneriacez, Bigmoneaceze, Scrophularinez, and 
Labiate, and, possibly, the crystalline powder of Sambucus, and 
many Solanacee. It may also happen that one is found in each 
cell, and this is the more common arrangement, especially with 
those that are grouped in druses, and with the short prismatic 
crystals of the bast cells. There is an interesting form of crystal 
which is surrounded by an integument of cellulose fixing it to the 
wall of the cell. These were first observed by Rosanoff, in Ricinus 
and Kerria Japonica, but afterwards by other observers in many 
more plants. Crystals are also formed in the walls of cells, in the 
epidermic cells of many species of Sempervivum and Mesembryan- 
themum, and in the liber fibres of many Coniferz. 
These plant crystals, by their regular occurrence or non-occur- 
rence, form constant characters of many families and groups of 
plants. Thus, in the Lemnaceze the genus Zemmna contain ra- 
phides, while in the genus Wo//fia they are wanting. In the stem, 
leaves, and fruit of Vitaceze every form of crystal is found. 
Very little is known of the physiological functions of these 
bodies. Oxalate of calcium is generally accumulated in those 
portions of the plant which have ceased to take part in its growth, 
and as it is often eliminated by the fall of dead leaves and old 
bark, it seems to be a useless product. It remains where it is 
formed, and is not dissolved again. It is also worthy of note that 
in the female flowers of Azcénus spheeraphides are plentiful, while 
in the male flowers they are almost wanting. 
J. &. M.S. Odober, 1882. 
PHE VORANGE COCEUS: 
By J. W. Gooen: 
Abstract of paper read before the Windsor and Eton Scientific Society. 
HE season for the importation of Oranges into England is now 
about to commence, and I beg to draw the attention of your 
readers to the immense pleasure they may experience in studying 
the various inhabitants of the surface of oranges of different kinds. 
Besides fungi and acari, the rind of the orange is infested with 
several species of Coccus: oranges from St. Michaels being the 
most prolific in microscopic specimens. On their surfaces can 
be studied the various stages of development of the Coccus, at the 
same moment, from the egg to the perfect male and female, and 
thus in the winter’s evening, when the whole of our own insect 
