No. 4-] 



BODIES OF THE INVERTEBRATES. 



157 



are intimately connected with the neuropil ; (3) they have small 

 nuclei, and very little cytoplasm ; (4) they are arranged m rows 



radiating from the neuropil. , .u a .u . 



While now at work upon a comparative study of the Arthro- 

 pod and Annelid brain, several preparations have been exam- 

 ined which throw light upon the distribution of the mushroom 

 bodies Since it will be some time before these studies can be 

 completed, certain discoveries bearing directly upon the distri- 

 bution of the mushroom bodies are described in this prelim- 

 inary paper. i ^.u^ 

 The author does not consider this the place to record he 

 bibliography, nor to discuss the technique, nor to acknowledge 



C."W 



p,Q. 3, _ Section through the brain of Xerets. 



his indebtedness to those who have in any way aided him m 

 these studies. All such information will be given m the final 



^The mushroom bodies are composed of two factors, cells and 

 fiber tracts. The cells are minute bodies having small nude, 

 and almost no cytoplasm. In this respect they resemble 

 Deiter's corpuscles of the vertebrate brain. Compact masses 

 of these cells crown each stalk. In these n,di the ce s are 

 arranc^ed in rows which radiate from the top of each stalk. In 

 each "half of the brain the principal fibers of the mushroom 

 bodies are collected in a stalk which lies, more or less erect, nr 

 a plane which cuts the longitudinal axis of the bram nearly a 

 right angles. The top of each stalk may be either unbranched 

 or bifurcated or ramosely branched. The lower portion of the 

 stalk usually gives rise to two branches, one passing outwards 

 (laterad) and the other inwards (mesad). 



