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in form. On the other liand, they differ entirely from the kinetosomes 
in behavior. So far as definite functions have been ascribed to them, 
they are thought to be concerned in certain constructive activities, such 
as the formation of inyo- and neurofibrillae and of the envelope of the 
middle-piece of the spermatozoön. They have no connection with the 
formation of the mitotie spindle, and although in some cases they seem 
to be distributed in a definite fashion to the daughter cells, their position 
during mitosis is quite unrelated to that of the division figure. A possible 
exception to the latter Statement is found in Benda’s (1899, 1903) con- 
tention that the rays of the polar aster consist chiefly of chondromites; 
but this is explicitly c-ontradicted by Meves (1908). 
Likewise suggestive of a similarity to the kinetosomes are the “chro- 
midia” which Richard Hertwig (1898, 1902) finds at one pole of the 
nucleus of Actinosphaeriwn, previous to the maturation divisions. The 
chromidia disappear before the beginning of the first division, but wliile 
they are disintegrating a granule which later functions as a central body 
appears among their fragments. The chromidia, like the chondriosomes, 
bear no relation to spindle formation, unless the central body is actually 
formed from their substance — a possibilitv that is denied by Gold- 
schmidt and Popoff (1907). Similar structures have been found in other 
protozoa, for example by Hertwig (1899, 1902), Schaudinn (1905) and 
Goldschmidt (1905); and in certain metazoan cells by Goldschmidt 
(1904) and Popoff (1907). t 
In their behavior, chromidia of whatever variety (idioclHomidia, 
trophochromidia, etc.) differ from the kinetosomes as markedly as do 
the mitochondria; and another important contrast appears in the faet 
that, as the observers of the chromidia seem to agree, they originate 
within the nucleus. Not only have I found, as already indicated, no 
evidence that the kinetosomes of Polytrichum are of nuclear origin; but 
no nuclei have been found, either in androgones or in vegetative cells, 
which contained at any time enougli stainable material to make such an 
origin conceivable. 
Other dark-staining cytoplasmic constituents of animal cells have 
been described, more or less similar to chondriosomes or chromidia, be- 
tween which and the kinetosomes any homology seems equally out of the 
question. Such are the “ergastoplasm” of Garnier (1897, 1900), the 
“apparato reticolare” of Golgi (1900), the “pseudoehromosomes” of 
Heidenhain (1900), the “centrophormia” of Ballowitz (1900 a — b), 
and the “trophospongium” of Holmgren (1902 a — b). On the other hand, 
a certain similarity to the kinetosomes is suggested by Platner’s (1889) 
