CELL FORMATION. .663 



the point to which the formed material corresponding to 

 each extended ; and each cell would then be exactly 

 analogous to the mucous-forming cells. In all of these cells, 

 of mucous membrane, tendon, cartilage, muscle, &c., there 

 is no abrupt demarcation between the germinal matter and 

 the formed material, but the one passes gradually into the 

 other. All living cells consist of matter in these two 

 different states ; the one being an active condition, vital ; 

 the other merely passive, in which no vital actions are 

 exhibited : upon matter in this first state, all growth, 

 multiplication, conversion, all life depends ; while in the 

 second condition, matter may exhibit many very peculiar 

 properties, but it does not grow or multiply, or convert or 

 form ; in short, it does not live^ though it may increase by 

 new matter being sui^eradded to it. 



Of the Nucleus and Niicleolus. — A mass of germinal 

 matter, besides increasing in quantity, may divide into 

 several, and thus cell-multiplication may occur ; and in all 

 cases it is to be observed that this multiplication is not 

 due to a "gro wing-in," or constriction of the cell-wall or 

 formed material, but entirely to changes occurring in the 

 germinal matter. In many cases a smaller spherical mass 

 may be observed in the centre of the germinal mass, 

 which often divides before the parent mass itself does ; 

 but it is by no means a necessary part of the process, for 

 division as often takes place where no such bodies are to 

 be seen ; and it frequently happens that these small 

 bodies may make their appearance only after the division 

 of the original mass. And again, within these, other still 

 smaller ones are sometimes produced. Tlie former are 

 termed nuclei, the latter nucleoli. These are to be regarded 

 as but new living centres appearing in centres already pre- 

 existing, and may perhaps mark the commencement of a 

 set of changes differing in some minor particulars from 

 the first that have occurred. But although both nuclei 

 and nucleoli are germinal or living matter, they are not 

 undergoing conversion into formed material. Nuclei do 

 not always exhibit their vital powers, but under certain 

 circumstances they may do so, and then they exhibit the 

 characters of ordinary germinal matter ; they absorb pabu- 

 lum and increase in size, and the original germinal matter 



