THE PRESENT POSITION OF CELL-THEORY. 307 



kugeln der Echiniden als ein gleichartiges Material 

 anzusehen sind, welches Man in beliebiger Weise, wie 

 einen Haufen Kugeln durch einander werfen kann, ohne 

 dass seine normale Entwicklungsfahigkeit darunter im 

 Mindesten leidet ". (The segmentation spheres of Echinids 

 are to be regarded as a homogeneous material which one may 

 roll amongst one another at will like a heap of balls, without 

 thereby destroying in the least their capacity for develop- 

 ment.) No hint whatever of rolling the nuclei through the 

 protoplasmic mass. The statement is made of Furchungs- 

 kugeln, that is of cells, and it is the cells that one may roll 

 about like balls. Not a bad argument for my contention, 

 that the blastomeres of many developing ova are disjunct. 

 If there were any doubt as to Driesch's words a study of 

 figures 39-68 which illustrate his paper would satisfy the 

 most exacting. The blastomeres are unusually distinct 

 from one another, especially in the embryoes illustrated by 

 figs. 63 and 67. Now for Hertwig: 1 "Bei den verschiedenen 

 Modificationen des Furchungsplasma werden die aus dem 

 ersten Furchungskern durch aufeinanderfolgendeTheilungen 

 erzeugten Kerngenerationen Theilen des Dotters, die in Eir- 

 aum eine sehr verschiedene Lage einnehmen, zuoetheilt und 

 mit ihnem zu einem zellkorper verbunden. Die Kerne wer- 

 den in Eiraum wie ein Haufen von Kugeln durch einander 

 gewurfelt." This is a very complicated German sentence 

 and might well lead to a misunderstanding, but it comes out 

 all right in plain English. "In the various modifications of 

 the divisional processes the nuclear generations, which are 

 produced by successive divisions from the segmentation 

 nucleus, are assigned to a portion of the yolk which occupies 

 very different positions within the limits of the egg, and are 

 bound with it to form a cell body. The nuclei are rolled 

 one over another within the limits of the egg like a heap of 

 balls." This passage is a summary of preceding state- 

 ments and inferences, and it might be held to bear a very 

 different meaning to that which it does bear ; the illustration 



1 O. Hertwig, " Ueber den Werth der ersten Furchungszellen fur die 

 Organbildung der Embryo," Arch, fur Mikr. A nat., vol. xlii., p. 662, 1893. 



