NOTES ON HISTOLOGY OF LINGULA ANATINA. 15 



bodies, in which one portion had already turned into fibres, while 

 the other remained in its orginal state (PI. I., Fig. 18) ; and in 

 other cases lying beside the perfect spindle bodies, the remnants 

 of compact bodies were found enclosed in the cell-membrane. 

 Although from the fact just described it is obvious that the 

 fibres are formed from the compact bodies, yet as to the manner 

 in which the growth in length of the fibres takes place I cannot 

 at present give any positive datum. Judging, however, from the 

 fact that while the compact bodies are directly imbedded in the 

 epithelium, and the spindle bodies are found in many cases lying 

 in a cavity, it is probable that the spindle bodies in their 

 growing stage emit a certain enzyme in order to dissolve the 

 neighboring cytoplasm and to take it up in themselves. Owing 

 to this nutrition, if it may be so called, the fibres of the spindle 

 bodies increase in length, at the same time becoming more or 

 less loose. 



d. What is the Spindle Body ? 



As above stated the spindle body is a metomorphosed blood 

 corpuscle, as Cori has observed in Phoro?iis ; that is, it is dis- 

 tinctly a cell, whose nucleus has degenerated and whose cytoplasm 

 has been turned into a fibrous structure. Since in every individual 

 the spindle bodies are produced in such great numbers in definite 

 regions, they cannot be looked upon as pathological products. 

 As they are enucleated cells they are destined sooner or later 

 to die out. They must, however, as such or at the time of their 

 formation, play an important part in the economy of Lingula. 

 It is certain that the blood corpuscles, leucocytes and spindle 

 bodies have their respective offices. Among several hypotheses 

 which suggest themselves in regard to the function the of spindle 



