Miscellaneous. 149 



containing clilorophyll of a pale green or nearly yellow colour ; — 

 these two parts form the oblong and slightly concave cup already re- 

 ferred to, at the bottom of which the vascular system, considerably 

 increased, is placed. Lastly, these vessels or reticulated cells are 

 covered by utricles of a carmine red colour. They form on the sur- 

 face of the cup, with the vascular cells which they enclose, a promi- 

 nent oblong gland, which is very elegantly bordered by the periphery 

 of the cup. 



The order in which these elements are presented, is not without 

 analogy with that which rules the arrangement of those of the stem 

 of a Dicotyledonous plant. Thus, in this respect, we may compare 

 these marginal glands (as has been done with leaves) to a segment of 

 the stem of a plant with two cotyledons. Thus at the exterior of the 

 gland there is an epidermis as in the segment of stem, and then a 

 layer of cells with green matter, representing the herbaceous en- 

 velojje ; then the vessels as in a stem ; and lastly, the rose-coloured 

 cellular tissue of the gland represents the pith. This comparison is 

 the more just, as the glands which fringe the leaf are, so to speak, 

 only the termination of the delicate teeth of the latter represented by 

 the pedicels, just as the marginal glands of the stipules of roses ter- 

 minate their much shorter teeth and even their nervures. — Comptes 

 Rendus, 25th June 1855, p. 1355. 



On a new Organ observed in Callitriche (C. platycarjja, ^'c). 

 By M. A. Chatin. 



The organs for which I propose the name of cystise give a whitish 

 appearance to the lower surface of the leaves in Callitriche, where 

 they exist in immense number. Under the lens they appear like 

 brilliant points, but the microscope shows that each cystia is a small 

 utricular apparatus presenting a closer esemblance to a doctor's cap*. 



The cystise are usually formed of eight cells, enlarged at their 

 apical or free portion, and vmited in a common, narrow circular base, 

 inserted into the larger, irregular cells of the epidermis. Towards 

 the middle and upper parts the cystia is adorned with ribs, like some 

 Cucurbitaceous and Euj)horbiaceou3 fruits (especially that of Hura 

 crepitans) . 



These organs are at first filled with a lifpiid, which is often rcjilaced 

 by gases (oxygen, nitrogen, and carbonic acid) towards the period of 

 flowering. The liquid usually contained in these organs contains 

 floating granules, which sometimes attach tliemselves to the walls, 

 and which are, for the most part, rendered brown by iodine. The 

 cystia; when filled with gas serve as floats ; their presence coincides 

 with the absence of j)neumatophora in the tissue of the leaves. 



The organogeny of the cystise is peculiar. Each of them, like the 

 stomata, arises from a cell which is distinguished by its small size 

 and its rounded form from the large tvvisted cells which constitute 

 the epidermis. Like that of the stomata, the original cell of the 



* The peculiar structure in question was described " y Dr. Laiikester in 1850; 

 8ee Ann. Nat. Hint. vol. vii. S. 2. p. 123. — Ed. 



