44 REPRODUCTION OF LOST PARTS chap. 



from suffocation is sometimes the result of the formation of 

 small blisters on the margin of the respiratory aperture. The 

 attacks of an internal parasite cause death in a singular way. 

 The upper tentacles swell at the base in such a way as to 

 prevent their extrusion ; digestive troubles follow, with rigidity 

 and loss of moisture, and death ensues in 2 or 3 days. 



Mr. Wotton isolated newly-hatched specimens, with the view 

 of experimenting on their power of self-fertilisation, if the 

 opportunity of fertilising and being fertilised by others was 

 denied them. One of these, after remaining in absolute solitude 

 for 10|- months, began to lay, scantily at first (11th January, 2 ; 

 25 th January, 2 ; 11th February, 2), but more abundantly after- 

 wards (3rd April, 60 ; 15th and 16th, 70 ; 29th, 53, etc.), the 

 eggs being hatched out in 42-48 days. The precautions taken 

 seem to have been absolutely satisfactory, and the fact of tlie 

 power of self-fertilisation appears established as far as Arion ater 

 is concerned. 



Braun took young individuals of Limnaca auricularia on the 

 day they were hatched out, and placed them singly in separate 

 vessels with differing amounts of water. This was on 15 th June, 

 1887. In August 1888 specimen A had only produced a little 

 spawn, out of which three young were hatched ; specimen B 

 had produced four pieces of spawn of different sizes, all of which 

 were hatched ; specimen C, which liappened to be living with 

 three PlanorUs, produced five pieces of spawn distinctly Lim- 

 naeidan, but nothing is recorded of their hatching. Self- 

 impregnation, therefore, with a fruitful result, appears estab- 

 lished for this species of Limnaea} 



Reproduction of Lost Parts. — When deprived of their 

 tentacles, eyes, or portions of the foot, MoUusca do not seem to 

 suffer severely, and generally reproduce the lost parts in a short 

 time. If, however, one of the ganglia is injured, they perish. 

 Certain of the MoUusca possess the curious property of being 

 able to amputate certain parts at will. When Frophysaon, a 

 species of Californian slug, is annoyed by l^eing handled, an 

 indented line appears at a point about two-thirds of the length 

 from the head, the line deepens, and eventually the tail is 

 shaken completely off. Sometimes the Proj^liysaon only threatens 

 this spontaneous dismemberment ; this line appears (always 

 ^ Nachr. Deuisch. Mcdak. Gcsdl. xx, p. 146. 



