4 O. C. GLASER. 



should find mitosis, but in this case the cell having the impulse 

 to divide, but being powerless to do so by mitosis, falls back on 

 the easier mode and does so by amitosis." That the food ova 

 "are on the road to complete breakdown" is unquestionably 

 true, but that the nuclear activities described should be looked 

 upon as futile attempts at segmentation, involving the substitution 

 of amitosis for mitosis, seems to me in the highest degree doubt- 

 ful. The ova of Fasciolaria that develop, are fertilized before 

 maturation, and as the food ova are not fertilized ('05) and con- 

 sequently not matured, attempts at cleavage are hardly to be ex- 

 pected. Among the conditions to which the eggs are subjected, 

 it is conceivable that they might find stimuli to mature without 

 impregnation, but the nuclear phenomena actually observed are so 

 utterly different from any of the other known kinds of nuclear 

 division, that to interpret the process as a futile attempt at either 

 maturation or segmentation, is to blind oneself with metaphor. 

 To include without qualification such phenomena as these under 

 the heading "amitosis," especially if it becomes established, as 

 seems likely, that under natural circumstances, direct nuclear 

 divisions may intervene between mitotitic divisions without wreck- 

 ing the ability of the cell to have progeny capable of further 

 differentiation, is certainly inexcusable. It may be etymologic- 

 ally correct to say that a nuclear division other than a mitotic 

 one, is amitotic, but to him who has formed an idea of direct 

 nuclear division from its more usual forms, the word "amitosis" 

 would certainly not suggest Fig. 2 of the present paper. It 

 will be necessary in the future to keep separate the normal and 

 the abnormal events in this field, and to distinguish physiological 

 from pathological amitosis. 



Zoological Laboratory, University of Michigan, 

 Ann Arbor, February 25, 1907. 



REFERENCES. 

 Brooks, W. K., and Herrick, F. H. 



'92 The Embryology of the Maeroura. Mem. Nat. Acad. Sci., V. 

 Child, C. M. 



'07 Studies on the Relation between Amitosis and Mitosis. Biol. Bull. , XII. 

 Glaser, 0. C. 



'05 Ueber den Kannibalismus bei Fasciolaria tulipa, etc. Zeitschr. f. w. Zool., 

 LXXX. 

 Osborn H.. L. 



'04 Amitosis in the Embryo of Fasciolaria. Amer. Nat., XXXVIIJ. 



