Nerve Cells of Tarantula 
WILLIAM A. HILTON 
G. Saint Remy ’90 and others have indicated at least two sizes 
of cells in the nervous systems of spiders. In tarantula there 
are numerous cells of small size and fewer of a larger sort. The 
functional nerve elements may be told from the others by their 
rather clear nuclei which contain prominent nucleoli. The large 
cell-bodies as compared with the size of the nuclei are also char- 
acteristic. No neuroblasts were clearly recognized in the adult 
spider. Two types of elements were seen which were thought to 
be connective in their nature, or neuroglia cells. In one kind of 
these the nuclei were rather clear, the cells widely scattered, but 
often partly joined together by their long slender processes. 
Some of these were found in the fibrous portion of the ganglion. 
In the other type of supportive element the cells are massed 
together in certain regions, the nuclei are filled with granules of 
chromatin and fine strands from the cytoplasm extend between 
the adjoining cells and penetrate into the fibrous area. These 
two types of elements form a framework or reticulum for the 
cells and fibers of the nervous system (Fig. 1, D and E). 
The smaller nerve cells seem to be rather simple for the most 
part. They appear to be unipolar with a large process directed 
towards the central fibrous mass of the ganglion. The nuclei 
of these are large with large nucleoli which contain one or more 
refractive spots. Fibrils are not so easily determined as in 
larger cells, but the nerve processes seem to be composed of 
many fine fibrillea. Little was learned about other points in the 
finer structure of these cells, but in preparations fixed in Flem- 
ming’s fluid there were numerous dark masses which were often 
‘seen. These were usually found in the cytoplasm on the oppo- 
site side of the cell from the nerve process. In appearance these 
resembled blackened fat particles (Fig. 1, C). 
The larger nerve cells were found grouped together or scat- 
tered about in the more ventral regions of the nervous system; 
some were found in the supraesophageal region, on the lateral 
