No. 2.] THE SPERMATOGENESIS OF LUMBRICUS. 293 



After chromic or picric acid it is small, more dense, and stains 

 more deeply. 



8th. There is a distinct difference between a Nebenkern 

 and the archoplasm. The latter gives rise to spindle fibres, 

 retracts parts of them into its substance and finally becomes 

 the middle-piece of the mature spermatozoon. The Nebe7iker7i, 

 on the other hand, is derived from interzonal fibres and dis- 

 appears after an apparently useless existence. 



Columbia College, 1894-95. 



