ON THE LIFE-HISTORY OF THE FORAMINIFERA. 139 



the ordinates give the number of chambers (containing proto- 

 plasm) of the different examples whose nuclei were measured. 



It must be observed, however, that these measures only 

 roughly indicate either the size of the nucleus or the bulk of 

 the protoplasm. The nucleus is generally an oval body, and 

 the " diameter " here given is the mean between the long and 

 short diameters as it presented itself in the specimen. In many 

 cases the nucleus would be seen endwise, hence the measure 

 of size here given is in many cases too small. Again, the 

 number of chambers is only a rough indication of the bulk of 

 the protoplasm, for it takes no account of the size of the vary- 

 ing megalosphere, or of the fact that in many specimens the 

 terminal chambers are empty, a condition due either to their 

 contents having been extended in the form of pseudopodia, and 

 hence torn off when the specimen was collected, or to other 

 causes. 



In the diagram two curves are given. The upper one embodies 

 the results obtained with 118 specimens preserved fresh from 

 the sea in the months of May and June. The lower gives the 

 results obtained from specimens kept in dishes in the laboratory 

 for three months, October to January. The dots indicate the 

 average size of the nuclei of the individuals having the same 

 number of chambers, the number placed by each indicating the 

 number of individuals from which the average is taken. It 

 will be seen that on the whole the direction of the curves is 

 upwards and to the right. In other words, as the protoplasm 

 increases in bulk the nucleus undergoes a corresponding in- 

 crease. 



In the specimens which had been kept alive in dishes the 

 nuclei are much smaller than in those killed fresh from the sea. 

 In these specimens so many of the terminal chambers were 

 empty that it appears probable that the protoplasm had shrunk 

 considerably as the result of the scanty food supply. As I had 

 no means of measuring the extent of the shrinkage, the in- 

 dividuals are tabulated according to the actual number of 

 chambers which contained protoplasm when they were mounted. 

 The case is. therefore rather understated, but the distance between 



