90 PROGKESS OF MICROSCOPICAL SCIENCE. 



is difficult, if not impossible, to obtain the ferment absolutely free 

 from sugar ; but a series of comparative experiments prove beyond 

 doubt that a sugar-forming ferment exists in the liver-cells. A calf's 

 liver was washed out for four hours by a stream of water directed 

 through its vessels. At the end of that time the water passed throiigh 

 quite colourless, but still contained sugar. A portion of the liver 

 soaked in alcohol and extracted with glycerine, was shown to contain 

 a ferment acting on starch, by the fact that, when equal quantities of 

 the glycerine extract were mixed in the one case with distilled water, 

 and in the other with starch paste, and allowed to stand for an hour, 

 the latter reduced a much larger quantity of Fehling's solution than 

 the former. The same liver washed for two hours longer yielded 

 water which now contained not a trace of sugar, but on being allowed 

 to remain for another hour, the water which was then passed through 

 it contained sugar. A glycerine extract of the liver so treated still 

 yielded a very appreciable amount of a ferment acting energetically 

 on starch. It would therefore ai)i5ear that the thoroughly washed and 

 blood-free liver still contains a ferment, and that this ferment is 

 formed in the liver-cells. The ferment formed here is partly poured 

 out with the biliary constituents ; as fresh bile, as Von Wittich has 

 shown, also possesses a diastatic action. 



The Microscopic Structure of Trap Mocks has been treated at some 

 length by Professor Hull, F.R.S., in a paper in the ' Geological Maga- 

 zine ' (Ajiril). The i)aj)er should be referred to as it is of some length, 

 meanwhile we may give the author's opinion as to the points specially 

 noticeable in reference to the above specimens, which may be regarded 

 as fair representatives of the Limerick Carboniferous melaphyres, 

 which are as follows : — 



1st. The glassy felspathic base with cells and tubes. 



2nd. The small quantity of augite, this mineral only occurring in 



the form of scattered crystals or grains. 

 3rd. The abundant infusion of chlorite, or more rarely epidote, 

 not only filling in cavities and interstices between the 

 crystals, but also replacing, in many cases, the original 

 minerals themselves (augite, olivine, &c.). 

 4th. The abundance of calcite, also due to percolation, and of 

 secondary formation. 



The Blood-vessels of the Membrana Tympani. — On this question a 

 very able paper appears in the ' American Journal of Medical Science.' 

 Dr. Burnett, who is the author, describes the arrangement of the 

 blood-vessels in the tympanic membrane of the dog, cat, goat, and 

 rabbit. These are arranged in a double series of looj)s, one of which 

 is comjiosed of vessels which run from the periphery directly toward 

 the handle of the malleus, and at a point from one-half to a third of 

 the distance between the periphery of the membrane and the handle 

 of the malleus return abru2)tly upon themselves, thus forming a series 

 of vascular loops round the edge of the membrane. The second series 

 of loops run from the handle of the malleus toward the periphery of 

 the membrane. In consequence of this arrangement a portion of the 



