CHROMIDIA AND THE BINUCLEARITY HYPOTHESES, 279 
Chromidia and the Binuclearity Hypotheses: 
A Review and a Criticism. 
By 
c. Clifford Dobell, 
Fellow of Trinity College, Cambridge : Balfour Student in the 
University. 
With 25 Text-figures. 
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Since the seed of the chromidia hypothesis was sown by 
Richard Hertwig in 1902, it has displayed such an amazing 
ability to absorb new or previously uncorrelated facts, for 
its own growth, that it now—in its more mature form—stands 
out as one of the most conspicuous objects in the whole wide 
field of cytology. And it has not—one may be allowed to 
think—merely flourished on the soil where none other could 
take root: it has also, in so doing, thrown into the shade 
many a less showy upgrowth. Yet it is not beyond the 
bounds of possibility that these smaller growths, being 
rooted in a firmer foundation of facts, may remain to ripen 
long after the chromidia hypothesis has fallen to the earth— 
from the sheer weight of its own overgrowth and the 
imsecurity of the ground in which it grew. 
The chromidia hypothesis took origin in protozoology. 
But it has since pushed out its roots so far that they now 
extend and ramify in other domains of zoology, and bacterio- 
logy. The result is that it is very difficult to view in its 
entirety. 
A most important offshoot from the original conception of 
chromidia has been a hypothesis of the binuclear nature of 
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