540 ANNUAL EEPOKT SMITHSONIAN INSTITUTION, 1912. 



structive appliances as are required to bring about the association of 

 the various elements entering into the structure of the organism. 

 The inclosure of the naked protoplasmic mass within a differential 

 septum (cell wall) through which only the simpler food materials 

 could gain an entry seems to me, therefore, a necessary act in the 

 evolution of Ufe. From tliis point of view, it matters httle winch 

 came first — cliromatin or cytoplasm. 



The argument put forward by Mr. Eccles in support of the con- 

 tention that nuclear material is the more primitive, based on the 

 l^reponderance of the open chain derivative arginine in the nucleus 

 and of benzenoid derivatives, such as tyrosine in the cytoplasm, can 

 not be regarded as valid. The difference between open and closed 

 chain compounds is not such that chemists can regard one as more 

 primitive than the other, except it be that the open is the first to 

 receive attention in the textbooks; and arginine, if not the most, is 

 one of the most complex products liitherto separated from albuminoid 

 materials, far more so than tyrosine: 



Arginine HN=C^j^2! CH^. CH2. CH2. CHCNH^). COOH. 

 Tyrosine HO. CqH^. CHj. CH(NH2). COOH. 



Arginine probably owes its value as a nuclear material to the many 

 points of attachment its nitrogen atoms offer — in other words, to its 

 complexity. 



Prof. JVIinchin would restrict the term "cell" to organisms in which 

 the protoplasm is differentiated into cytoplasm and nucleus definitely 

 marked off from one another and would therefore deny the term ''cell " 

 to bacteria and their allies. But bacteria apparently consist of 

 materials cUffering but httle in complexity from those met with in 

 liigher organism.s and they contain a variety of enzymes. The sepa- 

 ration of the nucleus within a special differential septum would appear 

 merely to mark it off as a separate factory witliin which special 

 operations can be carried on apart from those effected in the cyto- 

 plasm; the extrusion of nucleoli from the nucleus during the vege- 

 tative stage is particularly significant from this point of view, 

 especially as the nucleoh witliin and without the nucleus stain dif- 

 ferently.^ The differentiation of the nucleus, therefore, may be 

 merely a mark of a liigher stage of organization, but to make the 

 distinction suggested between bacteria and other forms appears to 

 me to be unjustifiable. 



From the point of view I am advocating, every organism must 

 possess some kind of nucleus — visible or invisible; some formative 

 center around which the various templates assemble that are active 



I See especially "Observations on the history and possible function of the nucleoli in the vegetative cells 

 of various animals and plants," by C. E. Walker and Frances M. Tozer, Quart. Joum. Exp. Physiol., 

 1909, 2, 187. 



