PRODUCTION OF SILICA BY THE ASSIMILATING PROCESSES OF PLANTS. 285 
any proportion. Fresh oil of turpentine dis- 
solves the first variety completely, but only 
dissolves a small portion of the other two, af- 
ter long digestion. The action of alcohol is 
similar. Schindler terms the last species, for 
the sake of distinction, insect copal. 
These facts 1 consider it proper to bring for- 
ward, because Dr. Hamilton denies that copal 
comes from India. Now, this opinion is at 
variance with the statement of Retzius, who 
called it Elaeocarpus copalliferus, because it 
afforded the gum copal. Dr. Roxburgh alle- 
ges also that the resin of the Paenoe is called 
East India copal. Mr. Turnbull of Mirza- 
pore informed Dr. Hamilton that some which 
he sent home for trial would not sell for copal, 
although it was allowed to be anime. “ The 
real copal and anime, ’ he adds, “ are Ameri- 
can productions.” The resin of the Paenoe, 
or Dripa (Vatena Indica) was probably used 
by the Brahmans of Malabar as an incense. 
The Paenoe is one of the finest ornamental 
trees in India ; and in the province of Canara 
it is usually planted in rows by the sides of 
highways, making remarkably fine avenues. 
I’he statement of Mr. Turnbull is not conclu- 
sive, because he does not state that its rejec- 
tion was the consequence of chemical exami- 
jiation. 
The paper of Dr. Daubeny, who is pro- 
fessor of both tl)e very extensive sciences of 
chemistry and botany, is devoted to an account 
of some researches carried on in prosecution 
of the curious facts pointed out by Schrader 
and others, who found that there was some 
reason to conclude that plants, in their assi- 
milating processes, produced silica. 
Their method of proceeding was first to burn 
the seeds and ascertain the quantity and nature 
of the residual earthy matter j then to sow a 
given portion of similar seeds in sulphur : and' 
then to ascertain the nature of the earths con- 
tained in the ashes of the plant. Dr. Dau- 
beny employed dififerent soils, and instituted a 
comparison between the effects of each. The 
materials of the soils were sulphate of stron- 
tian, Carara marble, sea sand, and mould. The 
results do not appear to lead to any new infer- 
ence. The author, however, concludes “ tlrat 
the roots bf plants do, to a certain extent at 
least, possess a power of selection, and that the 
earthy constituents which form the basis of 
their solid parts, are determined as to quality 
by some primary law of nature, although their 
amount may depend upon the more or less 
abundant supply of the principles presented 
to them from without.” 
The order Hydrophylleae was first pointed 
out by Mr. Brown, in his Prodromus Flor. 
Nov. Holl, under which he included the gene- 
ra Hydrophylkim, Phacelia, et Etlisia, and 
afterwards added Nemophila and Eutoca. 
Mr. Bentham, in the present paper, describes 
forty species belonging to these five genera, 
and anew one which he terms Emmenanthe. 
They all differ from their nearest allies, the 
Borragineue, in the capsular point, and copi- 
ous albumen, and the structure of the ovarium, 
in the Hydrophyllum, Nemophila, and Ef/isia, 
the placentae are broad, fleshy, line the whole 
ovarium, adhere at the top and basis only, 
being free from the parietes, and bear on their 
inner surface, each of them, from two to six- 
teen ovulae, placed in two vertical rows, one 
on each side of the central line. 
InjEtocflr, Phacelia, and Emmenanthe the pla- 
centae are linear, or slightly dilated, and adhere 
more or less to the parietes along their cen- 
tral line, bearing on their inner surface from 
two to fifty or sixty ovulae. 
I. Tlydrophyllum comprehends the species, 
1. Appendiculatum, from the Alleghanies ; 
2. Cayiadense ; 3. Virginicum ; 4.Macrophyl- 
lum, near the Columbia. 
II. Ellisia, I Nyctelea, Potowmac and 
Missouri ; 2. Ambigua, Missouri ; 3. Membra- 
nacea California ; 4. Crysanthemifolia Cali- 
fornia; 5, Microcalyx; 6. Ranunculacea. 
III. Nemophila. 1. Paviflora Columbia ; 
2. Pedunculata Columbia; 3. Phaceloides; 
4. Aurita California ; 5. Insignis California 
6. Menziezii. 
IV. Eutoca. 1. Douglasii California ; 2. 
Cumingii Chili; 3. Brachyloha California; 
4. Mezicana ; 5. Parviflora Pennsylvania , 
6. Loasaefolia California ; 7. Franklinii ; 
8. Menziezii California ; 9. Sericea ; 10 
Gj-and/yZom California ; 11. Z>ir;«rjccta Cali- 
fornia, 12. Phaceloides California. 
V. Phacelia. 1. Malvaefolia California ; 
2. Brachyantia Chili ; 3. Circinata Colum- 
bia ; 4. Integrifolia Platte ; 5. Ciliata Cali- 
fornia ; 6, Ramosissima California ; 7. Tana- 
cetifolia California; 8. Bipinnitifida Allegha- 
nies ; 9. Fimbriata Kentucky ; JO. Hirsuta ; 
11. Glabra. 
VI. Emmenanthe Pendulifiora Calaronia, 
Of these species 19 were sent from tha 
western parts of North America, by the in- 
defatigable Mr. Douglas, who, unfortunately, 
lost his life in the Sandwich Islands, during the 
prosecution of his botanical researches. 
The chief interest of the genus Diopsis arises 
from the extraordinary elongation of the sides 
of the head into two cylindrical horns, which, 
in some instances, are as long as the whole 
body, and at the extremity of which, the eyes, 
of a semi-globular form, are placed. The 
antennae, also, are inserted near the extremity 
of these protuberances, at a short distance be- 
fore the eyes. These horns, at first sight, 
might be mistaken for antennae, but they are 
inarticulated at the base, as well as along the 
surface; they have, therefore, no independent 
motion, their movement^ being, necessarily, 
accompanied by those of the whole head. 
When, however, we recollect that they con- 
tain not only the infinity of nerves of the com- 
pound eyes at their extremities, but also those 
producing the sensation, of which the anten- 
nae are the seat, we can easily imagine how 
necessary it is that the means of communica- 
tion with the remainder of the head should be 
unbroken by articulation. Mr. Westwood 
describes 21 species : 1. Ichneumonea Guinea. 
2. Collaris Senegal. 3. Pallida. 4. Nigra 
Sierra Leone. 6. Apicalis Sierra Leone. 
