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THE AMERICAN NATURALIST [Vol. XLI 



Carmarina hastata. He believes that it occurs in all striated muscle 

 fibers. 



The third series of preparations was of neurofibrillae, which M ere 

 shown with astonishing clearness. The coarse fibrils of the invertebrate 

 nerve cells (from Pontobdella and Lumbriciis), the finer fibrils of the 

 young dog, and the much finer fibrils of the adult suggest that a sub- 

 division of the fibrils accompanies the perfection of the nervous system. 

 The presence of neurofibrils is, for Professor Apathy, the essential 

 feature of a nerve cell. All cells have the property of contraction and 

 of conduction, but they are not nmscle cells unless they possess myo- 

 fibrillac, nor nerve cells unless they contain neurofibrillac. It remains 

 to be determmed whether the development of neurofibrillae accom- 

 panies the outgrowth of processes from the neuroblasts. 



Professor 11. G. Harrison of Yale University showed drawings of 

 the nerve cell processes sent out by detached cells of the spinal cord 

 of a tadpole. The portion removed was examined in lymph, mto which 

 the processes grew, each having at its distal end a group of slender, 

 radiating, amoeboid branches At time, these (h.uigid their shai)e 



minal branches were exhibited. In cmbi} u> IioiuwIihIi tin nnii..! 

 crest had been removed, iicncs witlmiii >li(ut!i wtn pukIikmI, 

 thus proving that nerve fii)crs iiui> ^icw wiihoiit tlx p.iitK ip.mon ot 

 sheath cells, and that the latter ate dcrnvd ( hicfly trom the neural 



Professor H. V Neal of Knox ( ..11. ^< IHiii.'i-^ .lu.ucd preparations 

 of embryos of Squalus, demoiisii.,iiiu^ ih. .mtjiuNMh of processes 

 from the neuroblasts. These pro.-.sxs .-..ulil Ix- traced lor some 

 distance through the surrounding tivsuc \\!ii. li t.x.k no part in the 

 formation of the ner^e fiber. Tin .,..<ini.n^ .li.>uul indications of 

 neurofibrils at an early stage. 



Professor A. Maximo^N of the ln.,.<n.l M..I1...I Uademy of St. 

 Petersburg exhibhed preparations ..t rabbit cmbi^os to sho^^ the 



