( 219 , 



adjoiiiijig- fells, wliicli tliev l»riii<i- in coiiiieclioii wilh c;U'h olhei'. 

 "CVtte zone des UaloJinels coiislituei-ait (loiic .... uiie réellc liniite 

 inteivellnlaire, mais mie limile iiK-<)in|»lèle." 



YoN Ebnkr ^J regai-ds llic cenieiillijies, llie "Sehaltsti'ieke", as brokcn- 

 off pei'inijsinninicnihi'anes, "ahgcrisseuc Pei'iniysiiiiiduiutcheii". 



SzYMONOWicz reproduees iii his textbook of hislology, whieh appeared 

 two yeai'S ago, a drawing of a section lliroiigh llie heart iimsele of 

 a hydropic coi-, in which the niyolilyrillae of one cell are seen clearly 

 to be in coiniection each with a lil»riila of the adjoining cell. 



For the embryonic heart the disappeai'ance of the cell bonnthiries 

 has been described by sevei-al authors in differeiit animals. 



Heidenhain "} reprodnces a section through the heart of a dnck 

 embryo three days old, in which no ti-aces of cellular limits arc to 

 be seen and the myofibrillae may he followed with great distinctness 

 vvithont interruption over a great area and the same tilu-illa passing- 

 different nuclei. 



According to Hoykr ^) in the cells of Purkinje the librillae (found 

 only in the peripheral region of the cell body) may be followed 

 without break through many cells. In young larvae of Triton Hoyer 

 found a complete absence of cell boundaiies. According to this 

 author the heart muscle is originally composed of isolated cells, 

 but these cells fuse during the later stages of development, and the 

 result is a syncytium. 



That this is really the case is shown by Godlkwski. A preliminary 

 communication ^) appeared simultaneously with the paper by Hoyer. 

 In the elaborate study ^) which appeared somewhat later, this process 

 of fusion of the cells of the heart muscle in young rabL)it and cavia 

 embryos is described very fully. Here the cells of the myocard 

 form at first a network composed of loosely arranged cells. By 

 division and gro\vth these cells get nearer to each other, and the 

 intercellular protoplasmic bridges thicken, the intercellular spaces 

 narrow^; "dadurch verschmelzen die Zeilen allmahlig in eine einheit- 

 liche Masse, in welcher die Kerne zerstreut gelegen sind. . . Schliess- 

 lich stellt die Anlage des Herzmuskels eine rollkumnien cinheitliche 

 Protoplasmamasse dar." In the protoplasm of this syncytium there 

 appear small granules, staining deeply with iron-haematoxylin ; during 

 the next stages of develojnnent these granules arrange themselves in 



1} Sitzungsber. Wiener Akademie. Math, naturw. Clause. Bd. 109 1900. Abtli. III. 



2) i.e. 1899 en 1901. 



3) Bull, internat, de I'Acad. des Sciences de Cracovie 1899 Nov., 1901 Mars. 

 *) Bull, internat, de I'Ac. des Sc. de Cracovie Mars 1901. 



5) Arch. f. mikrosk. Anat. Bd. GO, 1902. 



15 

 Proceedings Royal Acad. Amsterdam. Vol. VI. 



