94 Transactions of the Society. 



A Tentative Classification of Cell Elements. 



In the animal cell, be it a spleen, germ, nerve-cell or other 

 such structure, the cytologist may meet the following fairly sharply 

 marked bodies : Nucleus and cytoplasm, and in the latter, fat, yolk, 

 pigment, glycogen, mitochondria and Golgi apparatus. My own 

 researches have led me to classify the mitochondria and Golgi 

 apparatus (fig. 1) as the Protoplasmic (or living) Inclusions, and the 

 fat, yolk, glycogen and pigment as well as such bodies as zymogen 

 granules, as Deutoplasmic (Metaplasmic, dead) Inclusions. This 

 classification is given below, and I should mention that it is 

 entirely practical and pays no attention to the theoretical side of 

 the question. While the somewhat arbitrary classes Protoplasmic 

 (living) and Deutoplasmic (dead) may be artificial, and undoubtedly 

 are constantly being bridged by transitional substances, this system 

 has been temporarily adopted, and it merely remains to be seen 

 how far it will stand criticism of other workers. 



Nucleus. 



Cell Cytoplasm 



Centrosome. 



/I. Protoplasmiclnclusions (Living) : — 



(a) Mitochondria. 



(b) Golgi apparatus. 



(c) Possibly other less numerous enigmatic 

 protoplasmic granules (17).* 



2. Deutoplasmic Inclusions (Dead). 

 (a) Yolk. 

 {b) Fat or oil. 



(c) Glycogen or starch. 



(d) Pigment when not united with mito- 

 chondria. 



3. Ground cytoplasm or protoplasm (Living). 



In many animal cells one finds in addition zymogen, oxyphile 

 or basophile, and other (metaplasmic ? ) elements not mentioned 

 under the Deutoplasmic Inclusions. In all the cases of which I 

 know, these elements are secondary formations derived from 

 various sources in the differentiation of the cell. Thus the granules 

 in different sorts of leucocytes are developed during the differentia- 

 tion of the cell. The embryonic and indifferent cell does not 

 contain such derivatives, and it is to be understood that the above 

 classification does not particularly deal with all the many enigmatic 

 metaplasmic or deutoplasmic granulations which one meets quite 

 often in the differentiated somatic cells. It is also quite likely 

 (though still disputed) that mitochondria change into zymogen 

 granules and fat; Guilliermond shoM's that this applies to plant 

 starch, though we do not know so much about glycogen ; there 

 would hence be a transition between the cytoplasmic living inclu- 

 sions and the metaplasmic inclusions. This must be taken into 



* The italic figures within brackets refer to the Bibliography at end of the 

 paper. 



