ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 245 



(2) Other Cell-contents (including Secretions). 

 Epidermal Chlorophyll.* — Mr. S. Le M. Moore states that we owe to 

 Stohr the greater part of our knowledge about the chlorophyll of epi- 

 dermal tissues. Mr. Moore gives iu this paper the details of some 

 observations he has been making, and epitomizes his statements as 

 follows : — 



(1) As Stohr has shown, all but a small percentage of Dicotyledons 

 have chlorophyll in their epidermis ; but in about half of these chloro- 

 phyll is found on the upper surface as well as the lower. Out of 

 120 angiospermous species observed by the author, 102 had chlorophyll 

 in the epidermis of at least the under-side of the leaf; the number of 

 Dicotyledons was 115, of which 101 furnished epidermal chlorophyll. 



(2) Etiolin is formed in them, as in other chlorophyllous cells. 



(3) In a considerable number (34 per cent.) of species with epidermal 

 chlorophyll-grains, starch can be easily detected therein ; in 24 per cent, 

 a small quantity of starch is discoverable. Only 42 per cent, have 

 absolutely starchless grains. 



(4) There is no eventuality in the appearance of the starch, as De 

 Bary states ; for, on the one hand the grains can easily be discharged of 

 and recharged with starch, which, on the other hand, is absent from the 

 grains of some types through life. 



(5) In any given case it is impossible to say a priori from the 

 apparent depth of colouring shown by epidermal chlorophyll-grains, 

 whether starch will or will not be found therein. This seems to support 

 Pringsheim's theory of assimilation. 



(6) The substance coloured blue by iodine and showing the tannin 

 reaction with iron salts may perhaps be not tannin, but some substance 

 closely related thereto. 



Fluorescence of Chlorophyll.! — Dr. G. Cugini suggests that the 

 purpose of the fluorescence of chlorophyll is in connection with its 

 property of impeding the rays which are most efficacious in respiration 

 from penetrating the leaves, thus rendering the respiration less intense, 

 and making possible the process of the reduction of carbonic anhydride. 



Preparation of Pure Chlorophyll. J — After giving the history of the 

 various substances described under the name of chlorophyll by different 

 writers, and the mode of their preparation, Sig. L. Macchiati proposes 

 the following method for preparing pure chlorophyll. 



Fresh leaves are cut up into small fragments, repeatedly washed with 

 distilled water and then with anhydric ether to remove the waxy 

 substances, and are then boiled in alcohol until the solution acquires 

 an intensely green colour. The solution is filtered while boiling ; on 

 cooling, a dark-green precipitate is obtained, which is red in transmitted 

 light. This substance is identical with Bourgarel's erythrophyll. It 

 can be obtained perfectly pure, and crystallizes in square plates. When 

 this precipitate has been separated by filtering, the filtered liquid is 

 concentrated, and the residue washed repeatedly with distilled water. 

 The first portion of this water, which is of a golden yellow colour, may 

 be used for the preparation of xanthophyllidrin, The residue is then 

 dissolved in ether and allowed to evaporate, when needle-like crystals 



* Journ. of Bot., xxv. (1887) pp. 35S-G3. 



t Atti Congr. Naz. Bot. Critt. Parma, Sept,, 1887, pp. 55-9. 



X Malpighia, i. (1887) pp. 478-86. 



