333 



The Development of the Conuective Tissues 



In a tadpole 3 millimeters long the mesenchyme is well defined 

 around the spinal cord and brain, on the ventral side of the head and 

 around the chorda dorsalis. The individual cells are made up of large 

 irregular clumps of protoplasm filled with yolk discs and pigment gran- 

 ules, which almost hide the nucleus. At times the cells are arranged 

 in rows and two cells in apposition often appear to be Joined. This, how- 

 ever, is not frequent, and when they are united in this way they form 

 only a syncytial rod, for they are never united with cells on all sides to 



Fig. 1. 



Fig. 3. 



Fig. 1. Mesenchyme around the anterior end of the chorda of a tadpole 3 mm. 

 long. Zeiss ob. 3 oc. 4 ( x 500 diameters). Hsematoxylin and con^o red. 



Fig. 2. Mesenchyme around the anterior end of the chorda of a tadpole 4 mm. 

 long (X 500 diameters). The mesenchyme forms an extensive syncytium. 



form a syncytial spherule. The best place to study the mesenchyme 

 in this stage as well as in its further development is around the anterior 

 end of the chorda, for here it is quite transparent and a distinct 

 group of cells can be easily followed from stage to stage. Here the 

 cells are large and irregular, as shown in Fig. 1. When these cells are 

 examined carefully with a 2 mm. oil immersion lens it is seen that the 

 nucleus is almost obscured by yolk discs and pigment granules. The 



