148 



PEOKESSOR E. RAY LANKESTER. 



lage), as soon as formed by division of a previous cell, with a 

 definite, refringent, and firm capsule. The capsule of the mother- 

 cell thus becomes fitted iuternally with two secondary capsules, 

 each containing a nucleated corpuscle of protoplasm. The pro- 

 cess is repeated, and each time the products of division form 

 for themselves new, complete capsules, which, on account of 

 their differing refractive properties, can be readily distinguished. 

 The outermost capsules enlarge as the protoplasm within in- 

 creases in size, and gives rise to capsule within capsule. The 

 general disposition of these capsules is precisely like that of the 

 capsules formed by actively vegetating specimens of the Alga 

 Glceocapsa, or by some specimens of Vertebrate cartilage. The 



Fig 1. 



accompanying woodcut (fig. 1) shows the arrangement of suc- 

 cessive generations of capsules, the numerals indicating the 

 age of each capsule. This figure is copied from Gegeubaur's 

 memoir. It gives, in a diagrammatic form, the condition attained 

 by an isolated mother- capsule. After a certain size has been 

 attained, the outermost capsule breaks down, and the single 

 group arranges itself as two or four groups. But where the 

 capsules are closely pressed against one another in the main 

 tract of the axial tissue of the entapophysial ligament, there 

 is an irregularity of form produced, and an irregularity of 

 growth which renders it difficult to trace clearly the boundaries 

 of cell-groups. 



Moreover, there is not present in the axial tract of this tissue 



