1898.] 3Ir. Edicard A. Minchin on Living Crystals. 723 



WEEKLY EVENING MEETING, 



Friday, May 6, 1898. 



Sir William Crookes, F.PuS. Vice-President, in the Chair. 



Edward A. Minchin, Esq. M.A. Fellow of Merton College, Oxford. 



Living Crystals. 



Crystals are a class of bodies distinguished by many remarkable 

 properties. Their definite symmetrical forms, limited by piano 

 surfaces meeting at sharp angles, in conformity with some easily 

 recognisable type of geometrical figure ; their peculiarities of cleavage 

 and etching ; their growth and individuality, most strikingly mani- 

 fested in their power of regeneration ; and finally, their optical 

 properties ; each and all of these characteristics sufficiently mark out 

 the crystal from the non-crystalline body. None of these qualities, 

 however, are in any way due to the action of life. An ordinary 

 crystal owes its peculiar characteristics entirely to the action of the 

 laws of inorganic matter, laws which admit of being clearly formu- 

 lated and accurately calculated. 



Crystalline bodies are known, however, to occur which have been 

 deposited within living bodies, and which owe their origin to vital 

 activities. In such cases the crystal, while identical in its chemical 

 composition and molecular structure with crystals of inorganic origin, 

 may exhibit at the same time certain peculiarities which are due 

 entirely to the circumstances of its origin. In this way an oppor- 

 tuiiity is afforded of making an interesting and important comparison. 

 On the one hand we have the inorganic crystal, owing its striking 

 properties to the action of j^hysical laws which can be defined, cal- 

 culated and artificially reproduceil. On the other hand we have the 

 living crystal, as it may be termed (" biocrystal " Haeckel), which 

 exhibits certain additional features, the result of its origin amidst 

 conditions which no one has succeeded as yet in imitating or explain- 

 ing. Ti^e resemblances between the two kinds of crystal are such as 

 are due to the intrinsic properties of the material composing them ; 

 the differences must therefore be the effect of differences in the sur- 

 roundings in which the crystals arise. In other words, those points 

 in which a living crystal differs from a crystal of the same kind, but 

 of inorgiinic origin, must depend on the different activities of living 

 and lifeless matter. Hence a careful examination of the peculiarities 

 of the living crystal might be expected to throw considerable light 

 upon the nature of life and the properties of living matter. 



As an instance of p. crystalline body which occurs both as an 

 inorganic substance and as a living crystal, we may take calcite, 



