CONDITIONS OF CELLULAR IMMORTALITY 57 



salts exist in sea-water). After the stay of from 30 to 60 

 minutes in this solution, the eggs are transferred back to 

 normal sea-water, the transferring being in batches at 

 intervals of 3 to 5 minutes between each batch transferred. 

 It is then found that those eggs which have been just the 

 right length of time in the hypertonic sea-water develop 

 into perfectly normal sea-urchin larvae. In other words, 

 we have here a definite and known physico-chemical pro- 

 cess completely replacing what was, before this work, 

 universally regarded as a peculiarly vital process of 

 extraordinary complexity,, "probably beyond power of 

 human control. 



These three examples from Loeb's work on the sub- 

 ject of prolongation of life in the egg cell will suffice for 

 our present purposes. The lesson which they teach is 

 plain, and is one which has, as will be readily perceived, 

 a most important bearing upon the general concept of 

 life and death outlined in the preceding chapter. The 

 experiments demonstrate that the conditions essential to 

 continued life of the germ-cells outside the body are phy- 

 sico-chemical conditions, and that when these cells die it 

 is because the normal physico-chemical machinery for the 

 continuation of life has either broken down, or has not 

 been given the proper activating chemical conditions. 



Lack of space alone prevents going in detail into an- 

 other extremely interesting and important development 

 of this subject, due to Dr. Frank R. Lillie of the Univer- 

 sity of Chicago. He has, in recent years made a thorough 

 analysis of the biological factors operating when the egg 

 of the sea-urchin is normally fertilized by a spermato- 

 zoon. The conception of the process of fertilization to 

 which Lillie comes is ' ' that a substance borne by the egg 

 (fertilizin) exerts two kinds of actions: (1) an agglutin- 



