Trans. N. V. Ac. Sci. 154 Ap^. lo, 



among scientists, Mr. Wiechmann alluded briefly to four principal 

 theories of their orij;in. as (a) Terrestrial Volcanic, (b) Lunar Volcanic, 

 (c) Planetary, or (d) Cometary. There are many objections to the the- 

 ories that regard them as belonging to the earth or its satellite, on the 

 one hand, or as visitants from distant space, on the other ; and prefer- 

 ence is doubtless due to the view that these bodies belong to the planet- 

 ary system — perhaps as fragments of asteroids that may once have 

 collided. As regards the differences in their mineral and chemical 

 characters, which have led to various classifications, that of DaubreE 

 alone was given. According to him, meteoric stones are divided into 

 (i) Siderites and (2) Asiderites, according as they are composed of 

 metallic iron (wholly or partly), or do not contain that substance. The 

 former class, the Siderous meteorites, he again divides into Holosider- 

 ous, Syssiderous, and Sporasiderous — according to the amount in 

 which the iron is present. Various analyses of meteorites ware then 

 given. 



Mr. Wiechmann next proceeded to his own researches upon 

 meteorites, describing the manner of examining microscopic sections, 

 and certain adjustments thereof with reference to the use of polarized 

 light. A list of seventeen specimens was given, with the dates and 

 localities of their fall, from which he had prepared and studied numer- 

 ous sections, and also of various volcanic rocks examined in the same 

 manner for comparison. His attention had been chiefly given to cer- 

 tain very peculiar and characteristic forms which are found in many 

 meteorites, and to which he gave the designation of " Fusion-Struc- 

 tures." 



These structures are not crystal forms, as they lack the definite an- 

 gular character that belongs to the latter ; their outlines are often 

 rounded, and their aspect curiously suggestive of organic structures- 

 They might fall under Zirkel's definition of what he calls crystallites, 

 i. e., mineral formations possessing a radiate arrangement or grouping, 

 but not showing, either as a whole or in their parts, any regular prop- 

 erties or outlines of crystallized bodies. It is these " fusion-structures' 

 which have been regarded, in the recent well known work of OttO 

 Hahn, as representing true organic remains. 



The structures of this kind which Mr. Wiechmann had found in 

 the sections prepared by him, were then described, and illustrated by 

 a series of very finely prepared drawings, displaying their characters as 

 seen at various magnifying powers, from 75 to 1500 diameters. It was 

 shown that, in some cases, the organic aspect, presented under a low 

 power, disappears entirely upon greater magnification. After discuss- 

 ing these, the author declared his inability to discover any forms that 

 seemed really organic, and criticised various points asserted in Dr. 

 Hahn'S work, as distinctly negatived in his own observations. 



