480 MARIA M. OGILVIE GOEDON. 



certain number of these elements that it becomes embodied 

 in the hist-formeJ, finally removed from the living layer and 

 incorporated in the skeleton where good preparations enable 

 it to be recognised. It has then almost completely lost its 

 sensitiveness to colour, but it has preserved almost without 

 alteration its characteristic shape and its dimensions. 



"In the preparations which I have examined and winch up 

 to the present only concern a single species, I have found an 

 average of 150 scales unprovided with nuclei for one nucleated 

 scale. If one is justified in supposing that none of the nuclei 

 disseminated in the skeleton can escape observation, the 

 necessary conclusion would be that one determinate calico- 

 blast can, during its life, produce a total of about 150 cal- 

 careous scales." 



M. Krempf, in the foregoing description, appears to reserve 

 the term " calicoblast " for that evanescent stage in the pro- 

 duction of a skeletal element which immediately precedes its 

 actual separation from the ectoderm, in fact to limit it to the 

 nucleated fibre-containing body in the ectoderm. It must, 

 however, be remembered that von Heider gave the term to 

 fibre-containing bodies in which, as a rule, the nucleus was 

 shrunken or vanished. Thus so far as terminology is con- 

 cerned, I was strictly accurate when in my work I applied 

 the term to organic, fibre-containing bodies, whether nucleated 

 or non-nucleated; calcareous scales are most certainly what I 

 defined them to be — " calcified calicoblasts." 



It is another question whether each of them may be looked 

 upon as the morphological equivalent of a cell, or cellular 

 part. 



Until M. Krempf's evidence is given in full, it is impossible 

 to form any opinion regarding his statement of the oft- 

 repeated withdrawal of a nucleus into the ectoderm. Mean- 

 time, from the brief description he now puts before us, I see 

 no reason to infer that the presence of a spent nuclear body 

 in a skeletal element marks out that particular element as the 

 morphological equivalent of a cell, whereas the other skeletal 

 elements have not that morphological value. Each time that 



