No. 554] SHORTER ARTICLES AND DISCUSSION 127 



The segmented ovum divides into the cell-material of the individual 

 and into the cells for the preservation of the species. In both divisions 

 the cell-multiplication proceeds continuously, but in the body of the 

 individual division of labor occurs, while in the reproductive cells 

 simple division only takes place. Both groups of cells and their off- 

 spring are propagated quite independently of each other, so that the 

 reproductive cells have no share in the development of the tissues of the 

 individual, and no seminal or ovicular cell arises from the cell-material 

 of the individual. After the segregation of the reproductive cells the 

 history of the individual and that of the species are entirely distinct, 

 and because of this relation the "constancy" of the species is more 

 easily understood; that is. the sharp persistence of the phenomenon of 

 atavism by means of which ancestral traits are transmitted. For sperm 

 and ovum are not derived from the cell-material of the parent organism, 

 but have a common origin with it. However, since they are preserved 

 within it, they are subject to the conditions which modify the parent 

 organism; therefore the transmission of "acquired" characteristics is 

 not excluded. 



Xussbaum is said by some to be the first to suggest the idea of 

 the cellular continuity of successive generations, but this con- 

 ception is clearly implied in Virchow's aphorism 15 "omnis 

 cellula a cellula," and was fully stated in 1858 in the Law of 

 Genetic Cellular Continuity first clearly formulated by Vir- 

 ehow 16 as follows : 



Just as an animal can originate only from an animal and a plant 

 only from a plant, so every cell must arise from a preexisting cell. 

 Although there are individual cases in which strict proof is still want- 

 ing, yet the principle is firmly established that for all living beings, 

 whether they be entire plants or animal organisms or integrant parts of 

 the same, there exists an eternal law of continuous development. 

 gruppen und ihre Abkommlinge vermehren sieh aber durchaus unabhiingig 

 von einander, so dass die Geschlechtszellen an dem Aufbau der Gewebe des 

 Individmims keinen Antheil haben, und aus dem Zellenmaterial des Indi- 

 ^ iduu j Tls keine einzige Samen- oder Eizelle hervorgeht. Nach der Abspaltung 



getrennt, und wir glauben aus diesem Verhalten die 'Constanz' der Art, 

 d-h. die in der Ersrlieiming des Atavismus giplVlnde Ziihigkeit, mit der sich 

 die Eigenthiimlichkeiten der Vorfahren vererben, begreiflicher zu finden. 

 Denn Samen und Ei stammen nicht von dem Zellenmaterial des elterlichen 

 Organismus ab, sondern haben mit il.m gleichen rrsprung; da sie aber in 

 "an aufbewahrt werden, so sind sie auch den Bedingungen untenvorfen, 

 Ver C "b auf <1en elterlichen Organismus modificirend einwirken, weshalb die 



"Archiv fur Pathologic, A,.,it„mi>. Bd. ^. 1855, p. 23. 

 w "Di e Cellularpathologie im ihrer Begriindung auf physiologische und 

 Pathologische Gewebelehre, " Berlin, 1858, p. 25. 



