DO THE SIMPLER ANIMALS FEEL PAIX ? 349 



Grief incites the lachrymal organs, but tears flow from 

 vexation, from afliiction, from physical pain, or from 

 the efiect of an onion on the eyes. Pain incites the 

 vocal organs to a shi^iek ; but we hear persons, unhurt, 

 shriek, when they see others in danger. These illus- 

 trations suffice to make clear the difference between 

 movements which follow the sensation of pain, and the 

 movements which in themselves indicate it ; and enable 

 us to apply the Method of Exclusion, and show that 

 inasmuch as the very same movements are produced 

 by other stimuli besides pain, we are not entitled to 

 assimie that these movements necessarily indicate pain 

 in all cases. An insect will sometimes continue eating 

 if pinned to the table, and will only struggle to fly 

 away when the food is devoured. " Soft, lubricated, 

 and irritable as is the skin of the naked mollusc,'' says 

 Professor Owen, " there are not wanting reasons for 

 su^^posing it to be possessed of a very low degree of 

 true sensibility. Baron Ferussac, for example, states 

 that he has seen the terrestrial gasteropods, or slugs, 

 allow their skins to be eaten by others, and in spite 

 of the large wounds thus produced, show no sign of 

 pain/'* 



It thus becomes evident that shrinking, struggling, 

 crying, &c., are no certain indications of pain. Nay, 

 if we were to accept the shrinking as evidence, we 

 shoidd be forced to admit that the flower feels pain 

 when it shrinks on being touched. The other day I 

 was dissecting a Solen, which had already been dead 



* CWEX : Led, Oil Comparative Anatomy, p. 551. 



