108 SUMMARY OF CUERENT RESEARCHES RELATING TO 



zinc cLloropbyllan, and further with that of the leaf, apart from the dis- 

 placement towards red exhibited in the latter. 



Crystalloids in Pithecoctenium clematideum.* — Sig. E. Pirotta has 

 investigated the distribution and nature of the crystalloids in the above- 

 mentioned i^lant. As to distribution (a) in the root, they are much more 

 abundant in the adult than in the young form. In the parenchyma of the 

 deep layer of the cortex they occur abundantly, filling up the cells. They 

 are also numerous in the cambium cells, but are absent from the outer 

 woody portion and from the pith, (b) They are less frequent in the stem, 

 especially in the young branches and in the pith, (c) In the leaves the 

 crystalloids occur abundantly in the cortical parenchyma, but there is no 

 trace of them in the hairs. They are more abundant in the spongy than 

 in the palisade parenchyma, and accompany the bundles in considerable 

 numbers in the parenchyma and soft bast, (d) In the tendrils they occur 

 in scattered groups, especially in the cortical parenchyma and in that which 

 accompanies the bundles, (e) In the inflorescence there are not a few in 

 the flower-stalk, and especially just at the base of the flower. (/) They 

 occur more or less abundantly in all the floral organs, and abundantly in 

 the fruit, decreasing with ripeness. They do not occur in the seed. 



These spha3rocrystals vary considerably in size and colour. Numerous 

 fine crystalline acicular prisms radiate out from a centre, which corresponds 

 to a kind of solid amorphous nucleus within the cell. The crystalloids 

 form very simple bundles, or compact hemispherical or spherical bodies. 

 They are soluble in the living cell-sap, in boiling alcohol, glycerin, acetic 

 acid, ether, &c, and their various reactions are noted. 



The author believes with Hansen that the substance composing the 

 crystalloids is originally dissolved in the sap, from which it is separated in 

 drops, becoming subsequently crystalline. A list of various spheerocrystals 

 is then given, showing their wide and varied occurrence. 



(3) Secretions. 



Formation of Oxalic Acid in Vegetation.f — MM. M. Berthelot and 

 E. Andre have selected and examined at various stages of their growth the 

 following plants : — Runiex acetosa, Amaranthus caudatus, Chenopodium quinoa, 

 and Mesembryanthemum crystallinum. The juice of the first is always acid, 

 that of the second and third neutral or feebly acid, whilst that of the last 

 is neutral in the early stages of growth, but becomes acid as the plant 

 developes. The plants also differ very considerably in the ratio between 

 the soluble and insoluble oxalates which they contain. 



Bumex acetosa. — The seed or dried fruit contains 0*05 per cent, of 

 oxalic acid. In the early stage of growth (June 8th) the root contains 

 13 • 9 per cent, of oxalic acid 5 • 1 per cent, being soluble and the remainder 

 insoluble. The proportion of ash is 20*7 per cent., and some of the acid 

 is in the free state. When the plant is in active vegetation (June 26th} the 

 proportion is about 10 per cent., and it is especially abundant in the leaves 

 and branches, and least abundant in the root. The oxalates may exist in 

 the form of double salts of potassium, calcium, and magnesium, or in that 

 of ethereal salts which are ultimately decomposed in contact with calcium 

 compounds. When the plant begins to fructify (September 27th) the 

 absolute amount of oxalic acid has increased, but in much lower proportion 

 than the increase of the whole plant ; the percentage amounts to one- 



* Rev. Ital. Sci. Nat., ii. (1886) pp. 61-3, from Ann. 1st. Bot. Roma, ii. (1886). 

 t Comptes Rendus, cii. (1886) pp. 995-1001, 1043-9. Of. this Journal, vi. (1886) 

 p. 90. 



