384 JULIA ELEANOR MOODY 



of chromosomes, the X larvae, the product of artificial par- 

 thenogenesis or the fertilization of an enucleated egg-fragment 

 and the 4 X larvae obtained by shaking the eggs soon after 

 fertilization. As a result of the investigation, Boveri formulated 

 two laws based upon the comparative measurements of these 

 larvae which are as follows: ''The surfaces of the nuclei are 

 directly proportional to the chromosome number and hence 

 to the chromatin mass," and "The size of the cell in the sea 

 urchin larvae is directly proportional to the chromosome number." 

 Gerassimow ('01 and '02) found that, if in cell-division of Spiro- 

 gyra, the daughter nuclei were caused to remain in one of the 

 new cells, this cell in consequence grew abnormally large, and 

 he concluded, therefore, that the size of the cell is dependent 

 upon the size of the nucleus. 



Summing up the results of the work of Gerassimow ('01, '02), 

 of Boveri ('05) and of Popoff ('07), Hertwig in 1908 says: 



Das Neue, welche in der Lehre von der Kernplasma-Relation ge- 



geben ist, ist der Gedanke, dass der Massenverhaltnis von Kern zu 



k 

 Protoplasma, der Quotient -, d. h.. Masse der Kernsubstanz dividiert 



durch Masse des Protoplasma, ein gesetzmassig regulierter Faktor 

 ist, dessen Grosse fiir alle von Kerne beeinflussten Lebensvorgange 

 der Zelle, von fundamentaler Bedeutung ist. 



In this recent discussion of the kernplasma relation he dis- 

 tinguishes two definite periods of nuclear growth occurring in 

 the interval between consecutive conjugations; first, a 'funk- 

 tionelle-Wachstum,' a period of extremely slow nuclear growth, 

 accompanied by a rapid increase in volume of the plasma, re- 

 sulting in a disturbance of the normal kernplasma-relation : 

 Second, a 'theilungs-Wachstum', during which there is a rapid 

 growth of nuclear material by which the normal relation between 

 nucleus and plasma is restored, followed by cell division. 



Hertwig's conclusions find support in the recent work of 

 Popoff ('09) who, from a series of measurements made of Para- 

 moecium, found that the increase in size of the nucleus and 

 plasma between two consecutive divisions, measured at intervals 

 of one hour, did not follow a parallel course. During the first 



