Chondriosomes ( Mitochondria ) and their Significance. 97 
Meves from 1897 to 1911. Both writers showed that bodies like those 
of those described by the earlier observers occurred not only in 
the male cells of insects but in those of a large number of animals 
both vertebrate and invertebrate. 
Benda termed these bodies mitochondria (/utos thread, yo\ 'Sptor 
grain) from their tendency to occur in rows or filaments, and 
suggested that they constitute a new cell-organ probably character¬ 
istic of active cells, since he found that they occurred not only 
in the developing sexual organs but also in various kinds of somatic 
cells (young muscle fibres, leucocytes, etc.)—in fact, he believed 
that they might be found, at any rate in traces, in all cells rich in 
cytoplasm. Benda’s special service was the working out of special 
methods of fixation and staining 1 whereby the presence of mitoch¬ 
ondria might be demonstrated not only with special certainty and 
beauty in sperm-cells but in different somatic cells of a large 
number of animals. Meves suggested that Benda’s “ mitochondria ” 
were identical with La Valette St. George’s “ cytomicrosomes,” 
and he studied especially the behaviour of these bodies during 
mitosis of the spermatocytes of various animals. 
Benda had, in 1899, put forward the hypothesis that they 
represent a motor-organ of the cell, because in various animals he 
found that the greater part of the middle piece of the spermatozoon 
was developed from the mitochondria which at first are scattered 
in the spermatogenous cells. The behaviour of the chondriosomes 
in spermatogenesis differs somewhat in different animals. In many 
insects and worms they are scattered in the cytoplasm of the young 
spermatogenous cells as fine grains, but during the divisions of these 
cells they become elongated and divide by median constriction ; 
when the final division has taken place, the chondriosomes of the 
spermatid become aggregated into a rounded mass (“ Nebenkern ”); 
during the differentiation of the spermatozoon this mass divides 
into two portions which become elongated with the growth of the 
tail part of the spermatozoon, one end of each filament remaining 
close to the nucleus, and again become granular; finally the 
granules fuse together to form homogeneous filaments which by 
lateral fusion constitute a closed sheath around the axial thread of 
the tail. In mammals, etc., the chondriosomes do not show a 
“ Nebenkern ” stage but simply form a granular sheath around the 
axial thread of the middle portion of the sperm. 
Meves (1899) claimed that Benda’s motor-organ view is untenable, 
for he found that when the terminal portion of a living salamander 
sperm, which is free from mitochondria, is cut off, this portion 
remains capable of movement. However, Meves entirely agreed 
with a second suggestion made by Benda in his 1903 paper— 
namely, that in any case the portion of the sperm containing the 
mitochondria undoubtedly enters the egg at fertilisation, that the 
female sexual cells also contain mitochondria, that these bodies 
occur in large numbers in the blastomeres of the young embryo, 
and that they may play an important part in the conveyance of 
hereditary characters. Meves was led by cytological observations 
on various vertebrate embryos to support the hypothesis that the 
mitochondria function in this manner ; he found that these bodies 
occur in all the cells of the young embryo, but only rarely appear 
* See Lee, A. B. “ The Microtomist’s Vade-mecum,” ed. 6, 1905, p. 223. 
