64 
H. E. Jordan 
The theory of Meves that the mitochondria are bearers of hereditary 
qualities (in somewhat the sense that the chromosomes are regarded as 
such vehicles by Boveri, Wilson and their students) has been most 
extensively developed by Duesberg. Moreover, he has given much 
attention to the matter of contesting the validity of the position of the 
“Munich School” to the effect that chromidia (mitochondria) arise from 
tlie nucleus. It remains to define Duesbergb position and to estimate 
his objection to the nuclear origin of mitochondria as advocated by Hert- 
wig, GoLDScmxiDT and their students, witli whose opinion my obser- 
vations on the spermatogenesis of the opossum lead me to agree. 
Duesberg combats the idea of a striet cytoplasmic, as well as a 
nuclear, origin of chondriosomes. He holds that they are not formed 
from the cytoplasm of neuroblasts and myoblasts and fibroblasts, but 
that the fully formed indifferent chondriosomes simply here differentiate 
into neurofibrils, myofibrils, etc. ‘que ces chondriosomes sont en relation 
de continuite direct avec les chondriosomes des etats anterieurs» p. 121. 
According to Duesberg the various sorts of fibrils are “the product of 
an indifferent material, present in all embryonic cells, and capable of 
specific modifications in the different tissues” p. 121. On the basis of 
his observations on the sexual cells of the bee and the rabbit, he 
sliows that the chondriosomes are not a product of cytoplasmic dif- 
ferentiation of the somatic cells but that they are derivatives of the 
germ-cells. In the rabbit he was able to follow the successive steps in 
the transformation of the mitochondrial granulations of the unfecun- 
dated egg through the fertilization and Segmentation stages; thence 
as short rods to the 5th day, as “chondrioconts allonges et greles“ to 
the 8th day, and then through the final differentiation processes into 
ueurofibrillae and myofibrillae. The notion of the “continuity of the 
chondriosomes” is in direct Opposition to the discontinuity theory of 
GoLDScroiiDT (nuclear origin) as also with the theory of their cytoplasmic 
origin. Chondriosomes form an integral part of the protoplasm of the 
cell. From the cytological point of view their origin is like that of 
the nucleus or the remainder of the cell; “tont chondriosome provient 
d'un chondriosome anterieur” p. 122. 
Goldscitmidt Claims an identity between chromidia and mitochon- 
dria. Consequently the question for him remains as to whether they 
are nuclear in origin or constituent parts of cytoplasm. The theory that 
they originate in the cytoplasm by a process of transformation of the proto- 
plasm is very elosely akin to that which maintains their nuclear source. 
For a cytoplasmic origin by differentiation of protoplasm would occur 
