ARTIFICIAL PRODUCTION OF CALCAREOUS FORMATIONS. 121 



The calcosplierites consist, as do the laminse of which we 

 have just sjioken^ of a combination of calcium carbonate with 

 organic matter, which is the sole residue, when the calcareous 

 salt is removed by treating Avith an acid. If the develop- 

 ment have taken place in albumen, or a liquid containing 

 albumen, the fundamental organic substance remains with the 

 form and structure of the primitive calcareous bodies ; but 

 this fundamental substance is no longer albumen. The albu- 

 men is transformed into a substance, the chemical reactions 

 of which are those of conchyoline, and resemble those of 

 chitine. We will call it calcoglobuline. 



It is not, however, necessary, in order to obtain this sub- 

 stance, to cause albumen to combine with calcium carbonate, 

 and then to decompose the resulting compound. This round- 

 about way may be avoided by placing a fragment of chloride 

 of calcium in albumen. After some days the albumen dis- 

 solves the calcareous salt, and is transformed into calcoglobu- 

 line, which presents also, in part, a fibrillar structure, and, 

 after having been washed, gives all the reactions of that 

 substance. 



When calcium phosphate is liberated by the double de- 

 composition of calcium chloride and neutral sodium phos- 

 phate or ammonium phosphate, in a solution of albumen or 

 gelatine, no combination takes place with the organic matter ; 

 the precipitate formed consists entirely of crystals of neutral 

 calcium phosphate. The case is quite different if calcium 

 carbonate is at the same time produced in the liquid. The 

 precipitate then consists of a combination of the organic 

 matter with the two calcareous salts. If the calcium phos- 

 phate exists in large quantity, then the precipitate remains, 

 even after several weeks, in the amorphous or colloid state. 

 Neither crystals nor calcospherites are formed ; but if, on 

 the contrary, the calcium phosphate constitutes nothing more 

 than a small fraction of the precipitate, calcospherites are 

 formed, but among them are some which are the starting- 

 point of various ulterior formations. These may be reduced 

 to two fundamental forms, which, under certain definite cir- 

 cumstances, appear more or less perfectly developed. The 

 first form consists of plates, which sometimes attain a con- 

 siderable size, and are more or less curved. These plates are 

 either perfectly homogeneous, or else they shoAv fine fibres, 

 sometimes disposed in a parallel manner, sometimes divergent, 

 and concentric bands (Fig. 4). Plates of this kind have pre- 

 cisely the conformation of the calcareous svibstance which 

 constitutes the internal layer of the shell of the Lamelli- 

 branchiata, and which almost always forms exclusively the 



