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H. E. Jordan 
To recapitulate briefly, the mitochondrial elements which contribute 
to the formation of the spiral filament are traced back to the late growth 
period of the primary spermatocyte, where they appear to arise as true 
chromidia. A few may possibly trace their ancestry to still earlier sper- 
matogonial cells, and a small quota may have been added during the 
resting stage of the secondary spermatocyte and spermatid. 
Literature. Meves in his clasic memoir »Über den von la Valette 
St. George entdeckten Nebenkem (Mitochondrien-Körper) der Samen- 
zellen« gives a very complete critical review of the literature respecting 
chondriosomes up to 1900. More recently Dobell (1908) has written 
at considerable length on chromidia with reference more especially to 
their bearing on the binuclearity hypothesis (Kern-plasma-relation hypo- 
tliesis) of Hertwic. and Goldschmidt. Heidenhain (1907) in »Plasma 
und Zelle« also gives a masterly brief summary of the subject of mito- 
chondria (p. 410 — 421). The literature of the subject since 1900 has been 
most ably and completely reviewed by Duesberg (1910). For complete 
bibliographies respecting chromidia and mitochondria the reader is re- 
ferred to the above mentioned works. The more important still more 
recent papers on this subject are those of Meves (1910), Samssonow 
(1910), Rubaschkin (1910). Tschaschin (1910) and Heidenhain (»Plasma 
und Zelle«, Part. 2, p. 1079 — 1104, 1911). 
Discussion. Mitochondria were first specif icaUy described by 
Benda in 1897 in the spermatogenetic cells of the mouse. He found them 
abundantly present in all the generations of cells (also the Sertoli cells) 
and traced them into the spiral filament of the middle-piece. Cytoplasmic 
bodies apparently very similar to the mitochondria described by Benda 
had been noted by a number of earlier writers. Conspicuous among 
these was von Brunn (hence “bodies of von Brunn” used synonymously), 
who had observed them in seminal epithelium teased in serum and salt- 
solution. Recently Saisissonow (1910) and Meves (1910) have suggested 
their identity with the bioblasts (also nematoblasts and vegetativen 
Fäden) of Altmann (1893) and tlms ultimately with the intrafilar cyto- 
microsomes (of van Beneden). Such identity was still earlier urged in 
the papers of the Zoja Bros. (1891). Benda subsequently discovered 
mitochondria in the seminal epithelium of many vertebrates and in- 
vertebrates. Frequently the granules become aligned and form filaments, 
then known as chondriomites. The latter are regarded by Heidenhain 
(1907) as identieal with his pseudochromosomes and the chromidial threads 
of Goldschmidt (1904). The more important extension of Benda’s 
discovery was rnade by Meves. Recently these bodies have received 
