CONDITION OF EPIDERMAL FIBRILS IN EPITHELIOMA. 287 
(“ cyto-microsomes ”) occurring in the cytoplasm of those 
cells. This same body had been previously described by 
Biitschli under the name of Nebenkern, and A. V. Brunn, in 
1884, had shown that in the spermatids of the mouse, certain 
granules collect together to form the spiral sheath which 
envelops the intra-cellular part of the tail filament of the 
spermatozoon. 
Benda, in 1897 and 1898, in dealing with the histogenesis of 
the spermatozoa of various Vertebrates, drew attention to the 
constant presence of these granules in the cytoplasm of the 
spermatids. These granules he called Mitochondria, and he 
was able to trace their evolution up to the final condition in 
which they form the spiral sheath or thread of the spermato- 
zoon tail. 
In another paper (1899) he showed that the mitochondria 
occur in all the generations of the sexual cells of a large number 
of both vertebrates and iuvertebrates, and also that they are to 
be found in a variety of cells of the somatic tissues, such as 
striated muscle-fibres, leucocytes, marrow-cells, and in the 
epithelial cells of the kidney. 
But it is due chiefly to the researches of Meves and 
Duesberg that we owe the possession of the more important 
facts in connection with chondriosornes. 
The nomenclature now in general use is that of Meves, so 
that under the term (1) Mitochondria are classed the 
granules ; these may be arranged in chains or scattered 
through the cytoplasm; (2) Chondriokonts, rod-like bodies 
or threads, and which may sometimes arise from the fusion of 
rows of mitochondria; (3) Chondriosornes, a general term 
to include all cytoplasmic structures which are of the nature 
of mitochondria or chondriokonts. 
Meves (1908) showed that all the cells of the embryo chick, 
as early as the 15-hour stage, contain numerous chondriokonts 
and mitochondria in their cytoplasm, but with a noticeable 
differentiation in their arrangement in the three germinal 
layers, viz. the epiblastic cells contain mainly rods and threads 
(chondriokonts), whereas granules (mitochondria) are excep 
