146 THE CELL DOCTRINE. 



fore j'oungest cells are again spherical. Seventh, in 

 nervous tissues again, we meet cells which from their 

 prolongations, which may be one or many, are called 

 folar cells, and unipolar, bipolar, or multipolar, ac- 

 cording to the number of processes they possess. 

 Eighth, in the so-called connective tissue again, we 

 have a variety in the shape of the cells. Thus in 

 areolar tissue or connective tissue proper, we have 

 young round cells composed almost wholly of germi- 

 nal matter, exhibiting amoeboid movements and all 

 the characters of the leucocyte or colorless corpuscle 

 (Fig. 10, frontispiece), as well as the elongated spin- 

 die shaped nucleated cell, so characteristic as to have 

 long ago received the name connective tissue corpuscle 

 (Fig. 16, frontispiece, Fig. 18, B.). These latter cells 

 also possess prolongations, which unite with those 

 extending from adjacent cells, and being hollow thus 

 form a canalicular system, of exceeding fineness, 

 which is believed to be capable of conveying nutrient 

 juices in the absence of bloodvessels of sufficient size 

 to conduct the corpuscles of the blood. The appear- 

 ance of this system is shown in Figs. 16 and 19, from 

 Virchow's Cellular Pathology. Ninth, the cells of 

 striated muscular tissue exhibit a prolonged oval shape, 

 sometimes resembling that of the connective tissue 

 corpuscle, while the cells of unstriped muscular tissue 

 are typical spindle-cells, with bellied centres and 

 staff-shaped nuclei. 



Again, in cartilage we have cells exhibiting various 

 modifications of the spherical shape, while the cells 

 of bone give us a tenth form. These are contained 

 in correspondingly irregular cavities in its substance. 



