502 Prof. Gr. Tschermak on the Formation of 



existence, exhibit violent explosive activity, if we may judge by 

 analogy from the moon, which has passed through a stage of 

 much more intense volcanic activity than we have any ex- 

 perience of. Such smaller star-masses continue to lose in mass 

 by constant projection of fragments, until at last they them- 

 selves are resolved into small portions, and traverse the universe 

 in orbits of the most varied kind. 



We might feel inclined to recognize in the comets the 

 debris of such small star-masses, and to detect in their emana- 

 tions the last phase of that activity which we have described. 

 That, however, is beyond our province ; and it must be left to 

 those investigators who deal with the question of the nature 

 of comets to decide whether the observations already made are 

 calculated to establish such a connexion *. 



It will suffice here to have shown that the form of meteorites 

 may be assumed to be due to violent movements of the ori- 

 ginal star-mass acting from the interior towards the surface. 

 Similar movements are at present taking place on the earth 

 and on the sun, while at an earlier period it was by such move- 

 ments that the craters of the lunar surface were built up. 

 On different star-masses the cause of these movements may 

 be different ; and so long as the cause is in any instance un- 

 known it is permissible to term all these movements volcanic. 



Whether the action be simply explosive, hurling upward 

 the solid rock of the surface, or at the same time also erup- 

 tive, as on the earth, ejecting matter from the interior, in 

 either case a difference will be observed between the crust 

 and the nucleus of the rock. As meteorites reach us in the 

 form of angular fragments, it follows that the star-mass whence 

 they are derived must have possessed a solid crust ; further, 

 we must conclude that the interior was either not solid, or had 

 an altogether different constitution. 



Guided by their form we might trace the origin of meteor- 

 ites to smaller star-masses, constituted similarly to our earth, 

 which by volcanic activity have been gradually reduced to 

 fragments. The texture of the meteoric rock carries us a 

 step further towards obtaining a glimpse at the history of the 

 star-mass before its disintegration. 



It has already been stated that the constitution of many of 



* There are many who trace a connexion between the meteorites and 

 the shooting-stars because the atmospheric phenomena in each case are 

 almost entirely the same. As the connexion between the comets and the 

 shooting-stars had been discovered and explained by Schiaparelli, a rela- 

 tion between the comets and the meteorites followed as a matter of course. 

 A difficulty, however, is presented by the fact that the maxima of 

 frequency of star-showers in no way accord with the most abundant 

 aerolitic falls. 



