The Microscope. 167 



CYTOLOGY OR CELLULAR BIOLOGY. 



HISTORY OF THE SCIENCE (cONT'd). 

 THIRD PERIOD, 1865-1884. 



VI. — ORGANIZATION OF THE PROTOPLASM AND THE NUCLEUS THEIR 



CHEMICAL COMPOSITION. 

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



IN 1865 it was generally admitted that the fundamental proper- 

 ties of protoplasm in the two kingdoms of Nature are identi- 

 cal, but protoplasm was still considered to be hyaline mass, 

 homogeneous, and of visible structure. Even at the present day 

 many scientists hold this opinion, as may be learned by consult- 

 ing the writings of KoUmann, Strasburger and many others. 



Structure of protoplasm. — At first protoplasm was believed 

 to be arranged in concentric zones ; namely, an external zone, 

 considered to be more transparent and more homogeneous than 

 the internal mass, Avhich was to be granular, and often enclosing 

 vacuoles and other bodies derived from the protoplasm. Many 

 and various terms were also in use to designate these various 

 parts ; thus De Barry (1863) calls the clear, external zone 

 epiplasm ; it may be seen in the thecffi of Ascomycetes. Other 

 terms more particularly applied to the Protozoans and to eggs, 

 were Hautschichte, periplasma, ectoplasma, even protoplasm ; 

 but for the internal granular portion the following terms were in 

 use : metaplasma, endoplasma, deuto- or deuteroplasma, polio- 

 plasma, etc. Recently A. Brass has distinguished as many as 

 five concentric zones, and to each of them he gives a name, to 

 signify some supposed physiological function. 



Hanstein from a different standpoint distinguishes three ele- 

 ments in protoplasm, namely : 1st. The fundamental hyaline 

 mass distributed throughout the cell ; this he calls hyaloplasma.^ 

 2nd. The plastic fluid circulating in the threads and peripheral 

 sac ; this he calls enchylema. 3rd. The granules, or microso- 

 mata, scattered in the hyaline mass and involved in the move- 

 ment of the enchylema. Since then the terms hyaloplasm and 

 microsomata or simply microsoma, were used by nearly all 

 authors ; but enchylema was considered as belonging to the 

 hyaline protoplasm. When these distinctions became finally 

 established, a greater confusion arose in the terminology, and 



1 Pheffer (1877) had used this term in an entirely different sense. 



