INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 301 



much as from G to 9 per cent. The same relative increase in the amount 

 of lime also takes place with regard to the entire mass of the leaf, 

 again with the exception of the beech. An increase in the amount of 

 oxalic acid was observed only in the cases of the beet, rhubarb, and 

 beech ; and in the first the increase was subsequently altered to a 

 decrease. Some leaves, as those of the chestnut and elm, appear 

 never to contain oxalic acid. In those which do contain it, the 

 amount of lime is frequently, as in the beet and rhubarb, insufficient 

 to fix it. In others, as the bean and sainfoin, a large proportion of 

 the lime is present in the soluble form. 



These results do not confirm the statement commonly made that 

 the accumulation of lime in foliar organs is dependent on the pre- 

 sence of oxalic acid, or that all the lime present is in the form of an 

 oxalate. As little can it be maintained that oxalic acid is the sole 

 agent in the permanent absorption of lime salts from the soil, setting 

 free nitric, phosphoric, and sulphuric acid from their combinations. 



On the contrary, lime is absorbed during the whole period of 

 vegetation, especially before and during the time of blossoming, and 

 is distributed to all the organs. It appears to play a definite part in 

 the transport of organic substances from one organ to another. Tho 

 lime accumulates in the bark and the leaves, not in the wood, root, 

 tubers, or seeds, and is then commonly in combination with oxalic acid. 

 Oxalic acid is probably formed out of albuminous substances, possibly 

 also out of non-nitrogenous substances, in all organs where a new 

 formation or a transport of nutrient substances takes place. It may 

 diminish or entirely disappear even when united with lime. It may 

 also serve for the purpose of dissolving albuminous substances. 



Embryology of Gymnadenia conopsea.* — In a paper read before 

 the Sheffield meeting of the British Association, Mr. H. M. Ward 

 points out that the ovule arises on the placenta as a mass of cells 

 consisting of an axial row surrounded by an epidermal layer of cells 

 one deep ; the terminal cell of the axial row, just beneath tho 

 epidermal layer, enlarges and cuts off two cells at its apex, as 

 described by Strasburger. These cap-cells and the epidermal cells 

 become flattened and finally destroyed, as the cell which remains en- 

 larges and becomes the embryo-sac. The existence of the remains of 

 the cap-cells as refractive masses above the embryo-sac is evidence 

 against Vesque's view as to the origin of the embryo-sac by the fusion 

 of two or more superposed cells. The protoplasm of tho embryo-sac 

 then divides into two masses, one passing to each end of the sac ; they 

 there undergo further division into fours. Of the four nucleated 

 masses in the anterior part, one becomes tho oosphere or egg-cell, 

 attached to two others which have elongated as the " Gohiilfinncn," or 

 " synergidro " of Strasburger, and have become packed into tho top of 

 the sac ; the fourth remains suspended in tho protoplasm of tho sac, 

 and is said by Strasburger to fuse witli one of the similarly produced 

 masses below, the product becoming tlie nucleus of tho embryo-sac. 



* ' Rep. Brit. Assoc. Adv. Sci.,' 1879, p. 375 ; eeo also ' Quart. Joura. Micr. 

 Sci.,' XX. (1880) p. 1 (3 plutca and 4 figs.). 



