ITS CHEMICO-PHYSICAL AND MORPHOLOGICAL PROPERTIES 



47 



of their chemical properties have been distinguished above as linin 

 and nuclein, arrange themselves in the form of a more or less fine 

 framework structure. Figs. 23-26 show us examples of the various 

 modifications which may occur. 



Fig. 23 represents the nucleus of a cilio-flagellate organism. It 

 consists, like the chief nucleus of the Infusoria, of a small-meshed 

 framework of nuclein. Biitschli (II. 5) considered that it is in 

 the form of a small delicate honeycomb ; in his opinion the nucleus 

 is composed of extended faviform chambers, with three or more 

 sides, separated from one another by very delicate partition walls 

 of nuclein, and enclosing the nuclear sap, which is only slightly 

 affected by staining reagents. Similarly their upper surfaces are 

 separated from the protoplasm by means of a delicate layer of 

 nuclein, there being no distinct true nuclear membrane. The points 



Fia. 23. Nucleus of Cemtium tripos, 

 in which the faviform structure is very 

 plainly shown (after Biitschli, PI. 26, Fig. 

 14) : A ventral view ; B lateral view. Both 

 illustrations represent optical sections only. 



FIG. 24. Nucleus of a connective 

 tissue cell from the peritoneum of a 

 Salamander larva, with central cor- 

 puscles lying near it. (After Flemming, 

 Fig. 4.) 



where the partition walls meet are thickened like columns. The 

 appearance varies according to the point of view from which the 

 nucleus is seen, in consequence of the extended form of the faviform 

 chambers, which lie parallel to one another; a glance at Fig. 23 A, 

 .B, explains this. One or two nucleoli are to be seen in the cavity. 

 Fig. 24 represents the nuclear framework of a connective tissue cell 

 of a Salamander larva. It consists of a fairly close network com- 

 posed of extremely delicate threads. A few denser swellings 

 occur here and there, usually where several threads cross ; these 

 swellings retain the stain with especial tenacity. They consist of 

 collections of nuclein, and may look very like true nucleoli, which 



