264 Miscellaneous. 



The author sums up his results as follows : — The air of the swim- 

 ming-bladder presents a composition which may vary more or less, 

 relatively to the proportion of oxygen, under the following circum- 

 stances : — 



1 . The oxygen diminishes and disappears in asphyxia and other 

 morbid conditions. 



2. In the fishes with an open, as in those with a closed swimming- 

 bladder, the air is renewed without being derived from the atmo- 

 sphere, and the rapidity of this renewal is proportional to the vigour 

 of the fish. 



3. The new air presents an amount of oxygen far superior to the 

 proportion of that gas usually contained in the air of the swimming- 

 bladder, and also far superior to that contained in the air dissolved 

 in the water. — Comptes Rendus, Nov. 16, 1863, p. 816. 



On the Intercellular Substance and the Milk-Vessels in the Boot of 

 the common Dandelion. By Dr. August Vogl. 



The root of the common Dandelion possesses a central woody body, 

 surrounded by a thick, fleshy, strongly milky rind. If fine sections 

 of the root be treated under the microscope with various chemical 

 reagents, it appears that the intercellular substance occurring in the 

 root consists chiefly of pectose — the same substance which occurs in 

 unripe fruits and in turnips and carrots. By this it is shown that 

 this substance is by no means a secretion, but a product of conver- 

 sion of the cellulose of the cell-membranes. This conversion is che- 

 mical in its nature, and proceeds from without inwards. The pro- 

 duction of the milk-vessels in the root of the Dandelion stands in 

 connexion with this pectinic metamorphosis. The milk-vessels 

 which occur in this plant are perhaps among the most ramified 

 which occur anywhere in plants. They form main stems, which, 

 united into bundles, pass through the bark in a direction parallel to 

 the axis of the root. These main stems throw out a quantity of 

 lateral shoots — sometimes as short transverse branches of intercom- 

 munication, sometimes as csecal branches of greater or less length, 

 which are either inflated into a knob or drawn out to a hair-like 

 fineness at the extremity ; the different bundles are connected in a 

 tangential direction, and thus form large reticulated systems around 

 the woody nucleus. On examining into their origin, it appears that 

 their main stems are produced by the amalgamation of the so-called 

 conducting cells (Leitzellen, Siebzellen) which accompany the bundles 

 of milk-vessels, and probably constitute the organ for conducting 

 back the juices elaborated in the leaves. This fusion is induced by 

 the conversion into pectose of the membranes of the cells, consisting 

 at first more or less entirely of cellulose. — Bericht der hais. Akad. 

 der Wissenschaften in Wien; Math.-naturw. Classe, Dec. 17, 1863, 

 p. 10. 



