132 JOHN BEARD [February 



the amount one man can accomplish, even if he be conscious of the 

 existence and importance of the problems, is but the merest trifle, and 

 his labours would require an enormous comparative material, if the 

 results were to be of far-reaching import. 



These ' reasons, paradoxical though it may seem to be, impel the 

 writer to attempt some sort of consideration of the subject. It might 

 be made the work of a lifetime without evidence of exhaustion of the 

 subject. If we are ever to have a true and real comparative embryo- 

 logy of organisms, as well as the existing comparative embryology of 

 organs, many questions relating to the eggs of animals will need to be 

 cleared up. 



Facts are to be found for the seeking ; but, as every conscientious 

 embryologist realises, the search nowadays, especially if it be in some 

 definite direction, is often long and arduous. And the result may 

 often be a single fact and a dozen new problems. Moreover, most of 

 us have our plans of work mapped out for years to come, and have no 

 desire to forsake the plot of ground which we have diligently and 

 hopefully tilled, before we have reaped our little harvest. Therefore, 

 since the problem of the individuality of eggs with which we have 

 begun forms no integral part of our personal task, what we have to 

 say under this head partakes rather of the nature of incidental glean- 

 ings and musings than of deliberate investigation. We have attempted 

 to enunciate some of the problems without pretending to do more than 

 suggest what may be the nature of some of the solutions. 



Examine on the sea-shore the egg-capsules of a dog- whelk {Purpura 

 la/pillus). If one of the freshly-deposited cases be opened, in its in- 

 terior a large number of minute eggs may be counted. Some time 

 later visit the same spot and open others belonging to the same bunch. 

 The probability is that the enumeration of the developing organisms 

 in all the egg-cases of the bunch will not give as large a number as 

 that already recorded in the single freshly-deposited one. 



This is of course an old story. The cannibalism of the developing 

 young of the dog-whelk and whelk is one of the commonplaces of 

 marine zoology. 



Many years ago the writer endeavoured to study it for himself, 

 but as the examination of the cases was begun, when, as it turned out 

 subsequently, the eli urinative process was over, it was naturally not 

 observed ; although the facts were looked for until the young whelks 

 emerged from their cases. The process on that occasion was not seen, 

 simply because it happens at a very early period. One interesting- 

 little point did, however, reveal itself, that the number of young whelks 

 within an egg-case was fairly constant, about five or six. If the pro- 

 cess be mere cannibalism, it is not easy to perceive why it should stop 

 short, when some five or six larvae were left in the egg-case, why, as 

 almost always happens in the case of the Alpine Salamandra atra, 

 one should not devour the rest. 



