The Microscope. 235- 



a difference in the epithelium in the two parts. The muscular coat 

 too is thick and extends to close neighborhood with the body 

 wall. There are spaces between the pharynx and the body wall 

 across which threads of connective tissue reach ; the spaces 

 are the continuation of the body cavity, a large space in the pos- 

 terior regions of the body, and reduced to a very small one an- 

 teriorly (Fig. 1, cav). The brain as seen by the dissection has 

 disappeared, but on the ventral side is the section of the nerve 

 cord 'p n, which- continues along this side of the body to the pos- 

 terior end. It is seen in the dissections to be connected with 

 the brain by a cord of nerve tissue which runs around the throat. 

 Below the ventral nerve (still in figure 2), runs a small vessel 

 V. V. easily seen in sections. It is the sub-neural blood vessel. 

 Upon either side, in the body cavity, lie the portions of a tube 

 cut through in several places ; the pieces in section seem separate, 

 but they are different parts of the segmental organs, a pair of 

 which is present in each somite. A study of sections intermediate 

 between figures 1 and 2 will demonstrate the nerve cord which, 

 diverging from the ventral cord and embracing the pharynx, 

 unites above to form the brain. 



Having demonstrated these points with the low power we can 

 now apply the high power to the futher and more exhaustive 

 study of certain points in the histology of the pharyngeal region 

 of Lumbricus. 



CYTOLOGY OR CELLULAR BIOLOGY. 



VIII. — PROTOPLASM AND CELL-MEMBRANE. 



ORGANIZATION, CHEMICAL COMPOSITION, PHYSIOLOGICAL FUNCTIONS. 



REV A. M. KIRSCH, C. S. C. 



FROM the historical sketch of Cytology the reader has learned 

 that in the words of Sachs, " Protoplasm is a universally 

 known and yet an essentially unknown substance. " 



It would lead us too far to express all the views held concern- 

 ing this essential substance, necessary as a physiological sub- 

 stratum to those phenomena which are included in the compre- 

 hensive term life. Every investigator has his own views concern- 

 ing the nature of protoplasm, and it is not my intention to deny 

 any one the right of forming and holding an opinion ; nay, more,. 

 I claim also perfect freedom in accepting any opinion which best 



