lO CRYSTALS, AND ELEMENTARY GRANULES. [sect. 6. 



all present themselves in a form which is also met with in inor- 

 ganic nature, namely, as crystals and crystalline granules-, yet, in 

 man at least, such forms are very rare as normal histological 

 parts (otolithes, calcareous particles in ossifying cartilages), 

 while in animals, particularly in the invertebrate "siliceous °and 

 calcareous bodies of sponges, polypi, mollusca, etc., calcareous 

 crystals on the brain and nerves of the batrachia), and in patho- 

 logical formations (crystals of hsematine, bilifulvine, cholestea- 

 nne, calcareous concretions in joints), they are frequent pheno- 

 mena. On the other hand, amorphous bodies, consisting of organic 

 substances, are very common; that is to say, in almost all animal 

 fluids, whether contained in canals or inclosed in cells, as also in 

 many firm tissues, there are found in various, even in enormous 

 numbers, roundish granules, mostly of very small, scarcely mea- 

 surable size. Henle has called them elementary granules, and ex- 

 pressed the supposition that they are vesicles. This, however, is 

 not everywhere the case, inasmuch as it can be demonstrated that 

 many of these corpuscles possess no envelope. To this category 

 belong the fat drops which occur in many cells, and in numerous 

 secretions of glands, the pigment granules of the black pigment of 

 the eye, and of other coloured cells, the yelk granules of batra- 

 clnan and plagiostomian ova, and the proteine granules found 

 m most cells and juices of glands, as also in certain parts of the 

 gray substance of the central nervous system. Of the patho- 

 logical, yet very frequent formations, the granules of the co- 

 louring matter of the bile in the hepatic cells, the pathological 

 granular pigment and the deposits of fat granules, as °also 

 the colloid-granules in the thyroid and other parts, and the cor- 

 puscula amylacea of the central nervous system, are also to be 

 classified here, although they occasionally assume a very consider- 

 able size. All these granules are destitute of the phenomena 

 which are observed in the higher elementary parts, as of growth 

 from within outwards, of multiplication, of taking up and giving 

 off material, and are, in so far, still very closely allied to the 

 purely inorganic forms. Closely related to these formations are the 

 elementary fibres, isolated finer or coarser fibres, which are deve- 

 loped without the co-operation of nuclei or cells by the differentia 

 tion of a homogeneous substance. Such fibres are met with in the 

 matrix of many true cartilages, as also in many reticulated carti- 

 lages, and in many pathological formations, and may even present 

 a growth m thickness by apposition, as in reticular cartilages. 

 Elementary Vesicles are likewise very frequent, and most of 



