BLOOD AND BONE-MARROW OF FROG 469 
direct genetic relationship to such structures as nerve, muscle 
or connective-tissue fibrils, but are intimate cytoplasmic con- 
stituents most probably subserving general cell metabolism, not 
specific differentiations. On the other hand, we have the very 
suggestive fact that the axial filament of the flagellum of the 
sperm (comparable to a coarse cilium) does grow out from one 
of the partition products of the centrosome of the spermatid. 
The fact that a centrosome can still be detected in a ciliated cell 
is not disproof that some of the original partition products served 
as basal bodies for the development of the ciliary apparatus. 
Not all of the partition products need have been thus employed; 
several might have remained as discernible granules near the 
central portion of the cell. Nevertheless, Saguchi’s” general 
conclusion that the ‘‘occurrence of amitosis in ciliated cells is 
not owing to the lack of centrosome,” but is ‘due essentially to 
the degree of differentiation of the cell-plasm”’ (p. 262) is not in 
contradiction with my earlier suggestion that the primary com- 
mon cause of amitosis is some deleterious influence of variable 
type upon the centrosome. This might be narcotization, rela- 
tive lack of sufficient materials to meet metabolic demands as in 
conditions of very rapid growth or differentiation, lack of suff- 
cient supply of oxygen, or the presence of toxic substances as in 
degenerating or pathologic tissues. 
The theory that can in my opinion best harmonize the appar- 
ently contradictory observations that amitosis occurs in rapidly 
growing tissues, degenerating tissues, highly specialized cells 
(e.g., secretory, ciliated, granulocytes) and in tissues grown 
under experimental conditions (e.g., root tips grown in water 
with ether) is one expressed in terms of primary influence upon 
the centrosome, effecting either a loss of morphological integrity 
as by partition in ciliated cells and certain leucocytes, or loss of 
specific physiologic capacity as in narcotized, degenerate, or se- 
eretory cells. The effective factor may in the latter case still be 
fundamentally a disturbance of the optimum nucleo-cytoplasmic 
relationship (producing a nutritive want, subsequently affecting 
the centrosome), as recently suggested by Nakahara!’ for ‘se- 
cretory or reserve-forming cells,’ where he concludes that amitosis 
