468 H. E. JORDAN 
above, these types correspond with those found in the earlier 
and later stages respectively, of the first maturation spindle of 
the Cummingia tellinoides egg, where the pluricorpuscular is 
derived from the unicorpuscular sphere, and represents a dis- 
integration or partition product.* This conclusion respecting 
the significance of the pluricorpuscular centrosphere is sup- 
ported by the facts that the second maturation spindle of Cum- 
mingia has almost invariably this type of sphere and that the 
segmentation spindles again show spheres of both types. It 
would seem a legitimate inference that the two types of centro- 
spheres of the neutrophilic leucocytes of frog bear to each other 
the same genetic relationship, and that the pluricorpuscular 
variety also signifies disintegration. The medullary neutrophils 
support this inference; certain examples with lobulated nuclei 
contain a granular sphere (fig. 56), but here the sphere is smaller, 
the granules less numerous and more conspicuous. It seems 
very probable that the mitotic incapacity on the part of these 
cells results from an untoward influence upon the centrosome 
due to a relative lack of nutritive materials following the main- 
tenance of the high degree of specialization involved in the elab- 
oration of metachromatic granules. 
In a paper dealing with amitosis in the cells of the ioonee 
efferentes of the testis of the mouse, 4° suggested that the ami- 
totic division of these cells was a consequence of the loss of the 
integrity of the centrosome through partition into the basal 
granules which give rise to the cilia. While confirming the 
observation that ciliated cells of vertebrates do not multiply by 
mitosis, but may divide amitotically, Saguchi” claims to be 
able to demonstrate the presence and integrity of the centrosome 
in ciliated cells of vertebrates, and the origin of the basal gran- 
ules and the cilia from mitochondria. Apart from the fact that 
his illustrations are far from convincing, both as regards identi- 
fication of the centrosome and the genetic relationship between 
mitochondria and cilia, the divergence of such a process from the 
known functional behavior of mitochondria in general renders 
his claims dubious. The recent investigations on mitochondria 
have demonstrated that these cytoplasmic elements have no 
