392 TRANSACTIONS AND PROCEEDINGS OF [Sess. lvi. 



cells. Division and conjugation, however, will put a stop 

 to the individuality of the cell in question, but though such 

 has been lost, yet the individuality of the plasms constituting 

 the cell has been preserved, and it is this maintenance 

 of an individual plasm which, though it lead to the loss 

 or death of individual cell-life, yet serves to perpetuate the 

 species. 



As the various organs of a cell, we may consider the 

 endonucleolus, the nucleolus, the chromatin and achromatin 

 of the nucleus, the chromatin and achromatin of the cyto- 

 plasm, the various plastids, tlie paranucleus with its chromatic 

 and achromatic elements, and the cell-wall. Each of these 

 structures will have to fulfil definite functions, and probably 

 such functions as the dili'erent organs of a highly developed 

 animal or plant perform. We must localise in a cell the 

 channels in which the unclaborated food travels, organs 

 which will act on the food, organs which will distribute 

 the elaborated material, organs for respiration and secretion, 

 and a centre which acts as a trophic centre. Such a centre 

 would be the seat of the essential plasm of a cell, the plasm 

 which stamps a cell with the character of its species, which 

 is the common bond for the various organs, which regulates 

 income and expenditure, and which, through its organs, 

 becomes modified itself. 



In such a plasm would be contained the principle of life, 

 and well we might call it the " psychoplasm " of a cell. 



What is known about the various functions of the nucleus 

 has been brought together by liofer * in an admirable paper. 

 The author, after referring to work done by K. Brandt, 

 Nussbaum, Gruber, Verworn, Balbiani, Schmitz, Klebs, 

 Haberlandt, Korschelt, gives a very lucid account of his ex- 

 periments on Amoiha proteus, which led him to the conclusions 

 that the nucleus, firstly, possesses a direct influence over the 

 movement of the protoplasm, inasmuch as it is a regulating 

 locomotory centre ; and that, secondly, it influences the 

 digestion, as only by the co-operation of nucleus and proto- 

 plasm a secretion of digesting fluids is possible ; that further, 

 thirdly, the nucleus is neither concerned in respiration ; nor, 

 fourtldy, in the control of the contractile vacuole. 



* Ij. Hofer, Einfluss, il. Keriifi.s auf d. Protopl., in JcnaiscL. Zcitsclir. fiir 

 Xaturwiss., Bd. xxiv., Nov. IH'a'J, 



