630 A MARINE UNIVERSITY. 



Another line of research in the solution of which America, thanks 

 chiefly toE. B. Wilson, C^onklin, and Mead, is an acknowledoed leader, 

 is suggested by the following question: If a developing egg (for exam- 

 ple, the minute and delicate little surface-floating egg of some sea- 

 urchin) normalh^ divides into two, four, eight, and ad infinitum cells 

 to form the adult, what will happen if you shake these cells apart after 

 the first, second, etc., cleavage? 



The initial step is to stud}- the undisturbed process of cell division 

 through "cell lineage." The transformation of the simple fertilized 

 egg cell is always accomplished by splitting into man}^ cells, which 

 ultimately constitute the various tissues. It is obvioush" a matter of 

 great interest and importance to trace the lineage of the tissues back- 

 ward towartl the undivided egg. This has been done to such an extent 

 that we can designate the particular cells that give rise to the outer 

 covering of the body, to the nerves, alinientar}' canal, and to the repro- 

 ductive and germ cells. Ver}" .early in the histor}- of the embryo the 

 future functional and structural regions are marked ofl', and there is a 

 beginning of what Spencer termed the physiological division of labor. 

 Some biologists are inclined to carry this back still further into the 

 components of the egg itself. 



One would suppose that any rude disturbance of this beautiful pro- 

 cess would al)ruptl3^ terminate life. Quite the contrary; the general 

 answer to all such questions as the above l)eing that the unex])ected 

 will happen. Out of the patient observation of the unexpected, how- 

 ever, is coming the rationale of the life processes. 



The remarka))le general result has been obtained that upon shaking 

 apart the segments after the egg has divided into four or eight parts, 

 these isolated cells do not die, but again subdivide and form a lot of 

 twin or quadruplet indi\'iduals, as the case may be. In the early 

 experiments of this kind by Wilson and others each separate cell pro- 

 duced a minute Init entire individual. But when. Crampton happened 

 to repeat the experiment on certain snails' eggs, the main result was 

 that only one-half or one-fourth of an em])r3 snail was produced. 

 In sea-urchins, in which shaking also produced fractional animals, the 

 missing fractions were supplied })V regeneration — another verv strik- 

 ing example of Handet's aphorism. 



In 1000, Prof. Jacques I^oeb announced the remarkable discoverv 

 that in starfishes and other forms, by suital)le treatment with solu- 

 tions, not only of various salts, but also of such substances as sugar 

 and urea unfertilized eggs may give rise to swinnning Iarv;e. This dis- 

 covery, like mostotliers of similar character, was the natural se<iuence 

 of experiments which had started lin(>s of thought in this direction. 

 Richard Hertwig in 1896, in Germany, had shown that strychnine 

 starts the eggs of sea-urchins on the course of development. And 

 Moroan. Itctwcen ISDOand IIHIO. at Woods Mole, had shown that the 



