“As to the big Molucca crab (_Limulus_), I was struck (in 1882, at the Brighton Aquarium) with the extent of mutual assistance which these clumsy animals are capable of bestowing upon a comrade in case of need. One of them had fallen upon its back in a corner of the tank, and its heavy, saucepan-like carapace prevented it from returning to its natural position, the more so as there was in the corner an iron bar which rendered the task still more difficult. Its comrades came to the rescue, and for one hour’s time I watched how they endeavoured to help their fellow-prisoner. They came two at once, pushed their friend from beneath, and after strenuous efforts succeeded in lifting it upright; but then the iron bar would prevent them from achieving the work of rescue, and the crab would again fall heavily upon its back. After many attempts, one of the helpers would go in the depth of the tank and bring two other crabs, which would begin with fresh forces the same pushing and lifting of their helpless comrade. We stayed in the Aquarium for more than two hours, and, when leaving, we again came to cast a glance upon the tank: the work of rescue still continued! Since I saw that, I cannot refuse credit to the observation quoted by Dr. Erasmus Darwin, namely, that ‘the common crab during the moulting season stations as sentinel an unmoulted or hard-shelled individual to prevent marine enemies from injuring moulted individuals in their unprotected state’” (pp. 10, 12). #/ APPENDIX C IS LIFE WORTH LIVING? This grave question is, according to Mr. Herbert Spencer, one which must be “definitely raised and answered before entering on any ethical discussion” (Data of Ethics, § 9). He goes on to restate it in the form: Does life yield “a surplus of pleasurable feeling over painful feeling?” and he argues that “goodness or badness can be ascribed to acts which subserve life or hinder life only on this supposition” (§ 10). But can one really strike a balance between pleasures and pains in human life? Mr. Spencer himself admits, later on, that pleasures and pains, “unlike in their kinds, intensities and times of occurrence, are incommensurable” (§ 57). Moreover, the maintenance of life in the present day means passing it on for countless generations ahead, and how can we feel satisfied that the conditions then existing will make more for pleasure than for pain, even assuming that they do so now? The question, then, whether it is good to maintain life does not seem capable of philosophic decision on this ground.