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 pre- 

 vent 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 op- 

 portunity of fertilising and being fertilised by others was denied 

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

 lOJ months, began to lay, scantity at first (11th January, 2 ; 25th 

 January, 2 ; 11th February, 2), but more abundantly afterwards 

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

 ing hatched out in 42-48 days. The precautions taken seem to 

 have been absolutely satisfactory, and the fact of the power of 

 self-fertilisation appears established as far as Ai'ion ater is con- 

 cerned. 



Braun took young individuals of Limnaea auricularia on the 

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

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

 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 (7, which happened to be living 

 with three Planorhis^ produced five pieces of spawn distinctly 

 Limnaeidan, 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 ten- 

 tacles, eyes, or portions of the foot, Mollusca 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 Mollusca possess the curious property of being 

 able to amputate certain parts at will. When Propliysaon^ a 

 species of Californian slug, is annoyed by being handled, an in- 

 dented 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 Prophysao7i only threatens this 

 spontaneous dismemberment ; this line appears (always exactly 

 1 Nachr. Deutsch. Malak. Gesell. xx. p. 146. 



