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78 REPORT OF SCHIMMEL § Co. OCTOBER 1914/ APRIL 1915. 
Phyto-physiological Notes. 
Occurrence of resins and essential oils in plant tissues. 
In a combined article on micro-chemistry and the biology of vegetal matter, 
O. Tunmann’) discusses the occurrence of resins and essential oils in plant tissues”). 
The essential oils mostly accompany the resins and act as solvents. In the resiniferous 
glands often only resins or only essential oils occur. A separation of resin and 
essential oil can be effected by A. Meyer’s boiling and evaporation process, or by 
micro-distillation. Resins are recognized either by means of solvents or through copper 
salts; essential oils, through acids, as well as through Zimmermann’s osmic acid test, 
after the cuttings have previously been treated with Javelle water, in order to destroy 
the tanniferous substances, 8c. Fatty substances, which very frequently occur in 
resinous secretions, are recognized by means of their myeline forms. 
Many resins and essential oils which the chemist has to deal with do not agree 
in various respects with those in the secretion cells. Chemistry alone can here do 
but little, and micro-chemistry must come to the rescue. It has thus been found that 
the stearoptene of Bulgarian otto of roses originates from the layers of membrane of 
epidermis cells, which have become cutaneous. Stearoptene is therefore not a con- 
stituent of the oil in the living tissue. Tunmann arrived at this result through micro- 
chemical investigations of the sublimates of Rosa and Adiantum, whereas Tschirch 
came to the same conclusion through chemical examination. 
Tunmann turns against Giglioli’s indication that essential oils make the cell mem- 
branes permeable for substances which otherwise cannot interchange by osmosis. He 
also criticizes Charabot’s*) work and especially condemns his opinion that the essential 
oils are consumed during fertilization and seed formation. 
The author further points out that plants containing essential oils generally are 
such as require much sunshine, frequently representatives ot the Mediterranean flora. 
Whereas according to some authors the content of essential oils in plants decreases 
from South to North, Schtibeler quite generally presumed an increase of aromatic 
substances from South to North. Delpy and Hartwich found a larger number of oil 
glands on the leaves of Lavandula, Marrubium and Melissa of northern zones, whereas 
with Rosmarinus, Thymus, Salvia, Hyssopus and Origanum they were more numerous in 
plants of southern stations. 
According to Tyndall, the plants surround themselves with a layer of vaporous 
essential oils, thus protecting themselves against excessive heating through the sun- 
shine by day, as well as against too much cooling by night. It is true, objections 
against this view have been raised by Detto%). 
The glands of Myrtaceae and Rutaceae, which are provided with arrangements for 
evacuation, are, as Haberland says, means of protection against aggressive animals; 
we find similar protective weapons in animal life (musk-deer, &c.). 
More recent investigations have shown that one has to distinguish between resin 
glands, oil glands, starch glands and mucus glands and that the manner in which they 
partly or completely emit their secretions is closely connected not only with the chemical 
nature of these secretions, but likewise with their biological function. 
Alkaloids, vegetal mucous and glucosides are also minutely discussed in the article. 
1) Berichte d. deutsch. pharm. Ges, 24 (1914), eae: 2) Comp. Report April 1909, 118. — 3) Comp. 
Report April 1900, 50; April 1905, 90; October 1905, 89; April 1906, 104; October 1906, 106; April 1907, 127; 
October 1907, 136; November 1908, 162. — 4) Comp. Report October 19038, 82. 
