48 
they must belong to the same genus. I cannot, however, 
find any combining character, and their differences are very 
numerous. 
101. GONGORA maculata 3 var. alba. 
Among the Orchidaceous plants received by the Horti- 
cultural Society from Oaxaca, a singular variety of Gongora 
has made its appearance, with all the habit of the original, 
but with flowers almost white, except some pale dull wine- 
coloured spots on the sepals. It is a very graceful thing, and 
forms a good contrast with the old yellow and purple kinds. 
NEW VIEWS CONCERNING STARCH. 
In the last number of the Annales des Sciences there has 
appeared a very interesting paper by Mr. Mohl, concerning 
the action of iodine upon the elementary organs of plants. 
We hardly need inform our readers that starch is a product 
of the vegetable kingdom, found in the shape of oblong bodies 
of various sizes in the interior of cells, and that it has the 
property of becoming blue if acted upon by iodine; which 
immediately detects its presence. It has also been supposed, 
up to the present time, that starch is the only known sub- 
stance whose colour is thus affected when acted upon by 
iodine. It appears, however, from the researches now before 
us, either that other substances are so acted upon, or that 
starch exists in other states than that of the granules just 
spoken of. | 
Schleiden had remarked, that when cells are boiled in a 
ley of caustic alkali till they are dry, they are stained blue by 
the action of iodine, but lose the property by a prolonged 
ebullition in water. He did not however absolutely admit 
that by this process the lining of cells is changed into starch, 
but he thought it most probably was so, because when weak 
sulphuric acid acts upon vegetable tissue, and iodine is added, 
a small quantity of iodide of starch is obtained. He supposes 
that by this operation the primitive membrane of cells is also 
changed ito starch. He also considered that when woody 
tissue 1s converted into gum and sugar by the action of sul- 
phuric acid, that action is secondary, a conversion of it into 
starch always taking place in the first instance. Schleiden 
