ON THE PROTOPLASTID BODY AND THE 

 METAPLASTID CELL. 



IN the title which I had originally framed for the con- 

 tents of this paper, the words proto- and meta-zoa 

 stood in place of those employed, and I have made the 

 change in terminology out of deference to certain criti- 

 cisms which have reached me, concerning the impropriety 

 of an indifferent use of the terms proto- and meta-zoa 

 when speaking of both animals and plants. 



The word " plast " has great advantages; without an 

 affix it does not bind one to any numerical statement, and 

 it is sufficiently vague to cover most anomalies that are 

 likely to occur. Whatever it ought to mean, the really 

 important matter of what it has come to mean may be 

 gathered from the frequent use of the terms Mono- and 

 Poly-plastid, to distinguish between two well-marked types 

 of living forms. Of the first of these an amoeba forms a 

 typical example, and as the same structural elements which 

 compose this organism apparently constitute the individual 

 cells of the higher polyplastid forms, the constituents of the 

 monoplastid body appear to be equivalent to those of the 

 polyplastid cell. Plast becomes synonymous with cell, and the 

 difference between mono- and poly-plastid organisms appears 

 to be that the former are composed of one, and the latter of 

 many cellular elements. Now, although the appreciation of 

 this fact is exactly expressed by the current terms of multi- 

 and uni-cellular organisms, I have not adopted these, because 

 there are many monoplastid forms with affinities among the 

 polyplastids, which, through such a definition, would be 

 sharply excluded from them, and the inverse conclusion 

 equally applies. Therefore I have simply retained the old 

 affixes of proto and meta to designate the two great cate- 

 gories into which the various kinds of plastids appear to fall. 



The term proto implies that the protoplasts preceded 

 the metaplastids in point of time, and no objection is likely to 

 be made to it on that account, although I doubt if the 



