DEVELOPMENT OF LIVING MATTER. 51 



corpuscles ; and, lastly, we meet with pale, finely granular proto- 

 plasmic bodies devoid of nuclei and nucleoli. 



As the growth of the animal advances, no medullary spaces 

 are found in the bone, but canals for vessels instead. The medul- 

 lary elements ' in the space between the wall of the blood-vessel 

 and the border of the bone are mostly spindle-shaped, and either 

 yellowish, vacuoled lumps, or pale protoplasmic bodies, with and 

 without distinct nuclei and nucleoli. In all instances the com- 

 pact lumps, the pale protoplasmic bodies, the nuclei and nucleoli, 

 are bordered by light rims, which are traversed by radiating 

 spokes. 



In old animals, protoplasmic bodies of the above description 

 are rare ; in the marrow spaces of the shaft-bones they are usually 

 transformed into fat. 



My conclusion, drawn from these observations, is that the 

 protoplasma shows differences according to its age. 



The shape of the youngest protoplasm is that of a compact 

 lump of the living matter, with the following properties : It is 

 homogeneous, has a yellow tint of varying intensity and shade, a 

 considerable luster, and admits of being stained red by a solution 

 of carmine, and violet by a solution of chloride of gold. 



In this condition, with our present means of examination, no 

 reticulum is demonstrable. This condition is similar to that of 

 a tetanic lump of a contracted amoaba, and identical with 

 the condition of the living matter which I termed, in 1872, 

 " haematoblastic," in which the living matter produces both red 

 blood-corpuscles and the wall of the blood-vessel. For small 

 lumps of this substance, which are directly converted into red 

 blood-corpuscles, the term " hseinatoblastic " remains applicable, 

 though the hsematoblastic substance has a significance wider in 

 sense than it seemed to have at the time the name originated. 



The first noticeable differentiation in young protoplasm con- 

 sists in an accumulation of liquid in vacuoles. The vacuoled 

 condition of haematoblastic substance is the first step in devel- 

 opment, as observed in the lumps and nuclei of the tissues of 

 somewhat older animals. The first formation of the walls of a 

 vessel depends on this differentiation, inasmuch as the vacuole 

 represents the earliest cavity of a vessel. 



Owing to an accumulation of a liquid in several closed cavi- 

 ties of the young protoplasm, the living matter assumes the 

 shape of a frame- work. The points of intersection of the frame 

 becoming granules by a rupture of many of the walls of the vac- 



