308 
POPULAR SCIENCE REYIEW. 
among them certain minute bodies of well-marked and constant shapes. 
He detected, in June last, very small oscillating bodies which make up the 
hulk of the fovilla, and to these he gives the name Sotnatia. The form of 
the somatia is invariable in the same species of plants, and in plants of the 
same genus the forms appear to be nearly identical. The plants most care- 
fully studied were Cucurhita Tepo, Eschscholtzia crocata, OnagracecB, Portulaca 
grandijlora, Althcea rosea, whose somntia are figured as fusiform, discoid, &c. 
To observe these small bodies to the best advantage the author advises that 
a drop of distilled water should be placed on a few grains of the pollen on a 
slide, and then the cover should be pressed down so as to crush them. The 
•omatia are seen under a magnifying power of 800 to 1,000 diameters to have 
an oscillating motion which may be referred to the ^‘Brownian movement.”^ 
Treated with a solution of iodine, the colour of these somatia becomes 
blue ; but this tint is marked only in the central portion, while the outer 
part remains clear. 
Nervation of the Coats of Omdes and Seeds. — A brief article by Van 
Tieghem in Comptes Rendus,” August 14, 1871, and “Ann. Sci. Nat.,” 
November, 1872, and a long one in the latter Journal by LeMonnier (ap- 
parently Van Tieghem’s pupil), develope clearly the former’s view respecting 
the morphological nature of the ovule. He deduces the foliar nature of its 
envelope from its “ libero-vascular system,” which is that of the leaf. It 
answers, as has been before explained, to a marginal lobe of a carpellary 
leaf transformed and convolute around the nucleus, which, being destitute- 
of vascular tissue, is a “parenchymatous excrescence,” 2 itrichome, to use the- 
recent term of the Germans. Le Monnier sums up the conclusions thus i 
1. The ovule always consists of a lobe of a carpellary leaf, folded around a 
cellular mamelon inserted upon the medial line of the lobe : 2. in Angios- 
perms upon the upper or trachean face of the leaf ; in Gymnosperms upon 
the lower or Uherian face. 3. The embryo, although discontinuous from the 
tissues of the mother-plant, has determinate relations of position ; not only 
is the radicular extremity always directed to the micropyle, but its principal 
plane is generally perpendicular to or parallel with that of the seminal lobe. 
4. The primine, characterised by the presence of vascular bundles, is com- 
monly the only membrane which persists in the mature seed ; the secundine, 
except in rare cases (Euphorhiacefef is only a deduplication of the primine, 
and is mostly transitory. — (Professor Asa Gray, in “ Siliiman's Journal,” 
June.) 
CHEMISTRY. 
Action of Sulphuric and Hydrochloric acids on iron and steel. — At a compara- 
tively recent meeting of the “ Manchester Literary and Philosophic Institu- 
tion” Mr. William H. Johnson, B.Sc., called attention to the action of sul- 
phuric and hydrochloric acids on iron and steel. If after immersion for, saj', 
ten minutes in either of these acids, a piece of iron or steel be tested, its 
tensile strength and resistance to torsion will be found to have diminished. 
Exposure to the air for several days, or gentle heat, will, however, completely 
restore its original strength. On breaking a piece of iron wire after immer- 
