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Spindle Cells. 



The spindle cells of Amblystoma (fig. 6) are large elements which 

 are easily preserved by any of the common haematological methods. 

 They are round, elliptical or egg-shaped, have a relatively large nucleus 

 and numerous azurophil granules in the protoplasm, which is more 

 abundant at the poles of the cell than elsewhere. The polar cj'toplasm 

 is usually filled wdth granules which have a reddish-violet color wath 

 EoMANowsKY stains. A few dark-blue basophilic granules are usu- 

 ally scattered among them, and frequently one or two small vacuoles 

 are seen in the protoplasm at one or both ends of the cell. The cyto- 

 plasm which surrounds the long sides of the nucleus is very narrow, but 

 in spite of this fact the granules are very often seen to completely 

 surround the nucleus (fig. 6). In many cells the cj'toplasm is divided 

 into an ectoplasmic portion which is free from granules, and an 

 endoplasm which is filled with them. The ectoplasm is usually irre- 

 gular in outline and sends out pseudopodium-like processes which 

 give the impression that they are produced by amoeboid activity 

 (fig. 6). The endoplasm has a very regular contour, and its granules 

 are never seen to extend into the ectoplasmic processes. 



Azurophil granules are a common occurrence in the spindle cells 

 of the lower vertebrates, but usually there are only one or two of them 

 at either pole of the cell. Werzberg studied the spindle cells of a 

 great many Amphibia and other cold-blooded vertebrates but never 

 saw spindle cells in wdiich the granules are as numerous as they are in 

 Amblystoma. However, Wright figures spindle cells of Batrachoceps 

 attenuatus which are very similar to those of Amblystoma. He finds 

 a distinct division into a hyalin ectoplasma and a granular endoplasma 

 in which the granules are very numerous, but his figures do not show 

 the granules extending around the nucleus as they do in Amblystoma. 

 Wright finds, that with his methods, the granules have the same 

 staining reaction as the granules of the megakaryocytes of mammals, 

 i. e., they are azurophil. In Batrachoceps, portions of the cytoplasm, 

 including some of the granular endoplasm, are cut off from the cell 

 and float away in the blood stream. These isolated granular cyto- 

 plasmic masses resemble the blood platelets of mammals, and Wright 

 interprets them as such. The spindle cells, therefore, correspond to 

 the megakaryocytes according to Wright. In Amblystoma the 

 granular endoplasm and the hyalin ectoplasm have the same staining 

 reactions and structure as the corresponding parts of the spindle 



