Aug., 1847.] 251 



lion. This is probably the testicle, for it was the only thing I could 

 discover in connection with the genitalia to correspond to it. 



In two individuals only could I see part of the female organs. This 

 consisted in two sigmoid tubes or oviducts, which could be traced 

 from the generative orifice a short distance forwards, one on each side 

 of the penis. 



I could detect no traces of a nervous system. 



The eyes, so called, have been previously described. It is still a 

 question with many, whether these, as well as the corresponding deep 

 black points existing in very many of the lower animals of the inver- 

 tebrate series, subserve the purpose of eyes; and some anatomists 

 have even gone so far as to deny the sense of sight to the compara- 

 tively perfect eye of many gasteropodous mollusca. The experiments 

 which are made to test the existence of this sense in those organs for 

 the most part are exceedingly fallacious, generally being performed 

 by concentrating the light upon them through a lens. Insects, and 

 even serpents and frogs, I find will frequently bear the impression of 

 a sudden glare of light produced in this way without any inconveni- 

 ence, at other times they will seek to avoid it, but Helix albolabris 

 will occasionally retract its tenticle when so disturbed, and Phagocata 

 will frequently raise its anterior extremity and move from the too 

 great light. From their position, which is always such as to be well 

 exposed to the influence of the light, from their structure, imperfect 

 as it is in many cases, and their connection with the nervous system 

 when this exists, I am led to conclude that in all cases they are or- 

 gans of vision. 



The general sensibility of Phagocata is very considerable, that is 

 it contracts with great readiness from the slightest disturbance. The 

 contraction has much the appearance of being involuntary and is very 

 like that of the Medusae. When an individual is irritated at any point, 

 contraction commences and thence rapidly extends throughout the 

 animal, and the only appearance of volition is in the effort to escape ? 

 but if the touch be too rude, apparently involuntary contraction takes 

 place suddenly and appears to destroy all power of volition for the 

 moment ; the animal however soon revives from this state and glides 

 off with its accustomed speed. 



Some experiments which I performed upon Phagocata confirm the 

 statements that the Planarice are capable of repairing injuries. 

 When an individual is cut into two, both parts after a time become 

 distinct and perfect animals. Division carried to a greater extent in 

 some instances results in as many perfect animals as there are parts, 

 but generally I have found that when cut into more than three or four 



