332 



SCIJENCE. 



IVOL. I., No. 12. 



a horizontal direction. The axial relation a : b : c = 

 1.1626 : 1 : 1.5320. 13 ~ 89° 40'. 



Thomsenolite, — This mineral occurs in far greater 

 quantity than pachnolite. Its chemical composition, 

 from analysis by J. Brandl, is Na F . Ca F2 . Al F3 . 

 HjO. Heated in the closed tube, it decrepitates 

 violently, giving off acid water. The axial relation 

 a :6 :c = .9959: 1 : 1.08S7. /5 = 89°37i'; Besides the 

 perfect basal cleavage with mother-of-pearl lustre, a 

 second cleavage parallel to the prism was observed. 

 The habit of the crystals is prismatic, the prism 

 striated horizontally. 



Balstonite. — This mineral occurs crystallized in 

 isometric octahedrons ; and thus far its constituents 

 have been determined by a qualitative analysis made 

 on a very small quantity, and one imperfect analysis, 

 showing it to be a fluoride of aluminium, magnesium, 

 calcium, and sodium, with water. Carefully selected 

 material, submitted to analysis by J. Brandl, gave the 

 following : F (57.12) . Al (22.14) . Na (.5.50) . Ca (1.53) . 

 Mg (3.56) . Hi O (10) = 99.85, corresponding to the 

 formula, 3 (NasMgCa) F2 . 8 AlFj . 6H2O. The 

 mineral occurs intimately associated with the thom- 

 senolite. 



CMolite. — This is a tetragonal mineral, resembling 

 cryolite, occurring in the Ilmen Mountains, with axial 

 relation a : c = 1 : 1.0418. It seldom occurs in well-de- 

 veloped crystals ; and, when so, the crystals are small. 

 Occasionally it is met with in snow-white clusters 

 composed of an aggregate of minute crystals. The 

 various older analyses of the mineral vary very con- 

 siderably; and a new analysis, by J. Brandl, gives the 

 following result: F (57.30) . Al (17.66) . Na (24.97) = 

 99.93, corresponding to the formula, 5 Na F . 3 Al F,. 



Arksutite. — This mineral, which has for a long 

 time been regarded as a distinct species, is shown to 

 be based upon an incorrect analysis, and is probably 

 nothing more than a mixture of cryolite with pach- 

 nolite. 



Fluellite. — This mineral, which is one of the rarest, 

 is known in the form of minute sharp rhombic pyra- 

 mids, occurring with wavellite and other minerals 

 from Cornwall. With great trouble .12 gram was ob- 

 tained quite pure for analysis. This gave J. Brandl 

 the following: F (.56.25) . Al (27.62) . Na (0.56) [H2O 

 (15.55)] = 100. This agrees closely with the simple 

 formula, Al F3 . H2O. 



Prosopit. — This rare mineral, found at Altenberg, 

 Saxony, but not since 1866, occurs mostly altered 

 into kaolin, in some cases the crystals having a core 

 of unaltered material within them, while a few are 

 wholly unaltered. The crystals, while they have been 

 converted into kaolin, have retained their form most 

 perfectly. The crystals are monoclinic, with the axial 

 relation a:b:c = 1.318 : 1 : 0.5912. /3 = 86° 2'. Pure 

 material gave J. Brandl, upon analysis, F (85.01) . 

 Al (23.37) . Ca (16.19) . Mg (0.11) . Na (0.33) . HjO 

 (12.41) . loss regarded as oxygen (12.58) = 100, corre- 

 sponding to the formula, Ca AI2 (F, O H).,., in which 

 fluorine and hydroxyl are isomorphous. 



S. li. Pbnfield. 



COLOR AND ASSIMILATION. 



A NEW method of measuring the effect of rays of 

 different degrees of refraugibility upon the assimila- 

 tive activity of vegetable cells has been recently 

 devised by Th. W. Engelmann of Utrecht. It will 

 be seen that the method is simple, and probably of 

 wide applicability. It consists in the use of a few 

 iminjured cells, — for instance, of some filamentous 

 alga, — placed in water which contains bacteria. If 

 oxygen is evolved from the cells, as in assimilation. 



the bacteria, which up to that time may have been 

 quiescent, become extremely active, and the activity 

 is greatest close to the assimilating cells. If light 

 be now withdrawn, the supply of oxygen is soon 

 exhausted, and the bacteria again become quiet, re- 

 suming their activity as soon as the slightest trace 

 of free oxygen is accessible to them. By their pres- 

 ence it is possible to detect, according to Engelmann, 

 the one trillionth of a milligram of oxygen. 



Supposing a long filament of some alga is thus ar- 

 ranged under the microscope, and light passes through 

 the slide, the character of the light is seen at once to 

 have a very marked effect upon the movements of the 

 bacteria. If the light has first been passed through 

 a direct-vision spectroscope placed under the stage of 

 the microscope, so that the filament lies in the length 

 of the spectrum thus produced, the bacteria are seen 

 to cluster immediately in certain parts of the spec- 

 trum, to the exclusion of the others ; and the inference 

 is not unfairly drawn, that they go where oxygen is 

 most abundant. To the facts thus presented in an ear- 

 lier paper, Engelmann adds, in the Botanische zeitung 

 (Jan. 5 and 12, 1883), some curious observations re- 

 garding the assimilative power jjossessed by vegeta- 

 ble cells of different colors. In brief, his results are 

 the following : only those cells which contain chloro- 

 phyll or its equivalent in the protoplasmic body have 

 any power of evolving oxygen; a colorless cell, or 

 one which has coloring-matter only in the cell-sap, 

 cannot evolve oxygen under the influence of any rays 

 of light. This has a direct bearing upon the so-called 

 'screen' theory of Pringsheira, according to which 

 the pigment acts only as a screen to diminish the 

 otherwise too intense effect of light. It may be stated 

 that Pringsheim suggested, that, by passing through 

 a thin layer of solution of chlorophyll-pigment, the 

 light would be so tempered as to bring about assimi- 

 lation in colorless protoplasm. Engelmann shows 

 that this is not likely to happen under any conditions 

 of screening. 



Furthermore, in experimenting upon algae of dif- 

 ferent colors, he found that the assimilative activity 

 is not in the same part of the spectrum for all cells. 

 For instance : the greatest activity for red cells is in 

 the green; for green cells, in the red; for bluish 

 green, in the yellow; and, for yellowish brown, in the 

 green and red; or, in general, in the color that is 

 almost or completely complementary to the color of 

 the cell. To state this in another form, it may be said 

 that the rays of the spectrum which effect the work 

 of assimilation are identical with those which are 

 absorbed by the chlorophylline coloring-matter. 



It may be added that a large number of Efngel- 

 mann's experiments were made by the use of Edison's 

 lamp. In Pfliiger's archiv for Jan. 10, the same 

 author has a paper on a bacterium which he has found 

 to be extremely sensitive to light, and which has been 

 named B. photijmetricum. There are a few points 

 in that communication which are not wholly in har- 

 mony with the facts stated above; but, as they are 

 of minor consequence, they may be passed over now 

 without further mention. Geo. L. Goodale. 



LARVAL STAGES AND HABITS OF THE 

 BEE-FLY HIRMONEURA. 



Nothing is yet known of the first larval stage of 

 the bee-flies. I have expressed the belief that future 

 observation would show that there is a parallel be- 

 tween the Meloids and the Bombyliids, in that the 

 first or newly-hatched larva of the latter would differ 

 from the clumsy, partially parasitic, full-grown larva, 



