236 Lilian J. Gould's e.rpcri incuts 



at once, and it seemed to me that the likeness might 

 possibly be a protective one. The idea was confirmed 

 by the fact that I found the green larvae, though 

 adopting the spiral attitude on leaves, hung compara- 

 tively seldom, and never spun at all. I cannot say 

 positively that the brown larvae never spun when I did 

 not observe them, but I do not think that they did. At 

 the same time it has been represented to me that it is 

 difficult to conceive how a voluntary motion of the kind 

 can be caused by a larva hanging loose at the end of a 

 thread, and also difficult to see how the larva3 can have 

 become aware of the presence of what they supposed to 

 be an enemy unless by vibration, which did not seem to 

 be the case, or by shadow, which is possible, as I looked 

 very closely at them. I hope to investigate the subject 

 further, and to endeavour to show whether the movement 

 is related to the existence of some disturbance, as, if so, 

 I think it would prove strongly protective. 



If the resemblance really is to objects spinning in trees 

 and bushes, the fact that the green larvaB do not spin 

 is exactly what we should expect, for green leaves or 

 objects are rarely, if ever, seen in the position described. 

 A green larva would be rendered more easy of detection 

 by the habit, for it would attract the attention of enemies 

 by spinning, and would run some risk of doing so by 

 hanging at all ; while on green leaves it is sufficiently 

 protected by its colour. The suggestion is, however, a 

 purely tentative one, and the observation has not much 

 value without further investigation as to the exact nature 

 and causes of the movement. 



2. Notes upon the red spots in Smerinthus larvae. 



On July 30th, 1890, at Mr. Poulton's suggestion, 

 twenty-three newly-hatched larvae of Sinerintluis tilice, 

 the parents of which had been spotted as larv;T3, were 

 sent me by Mr. R. C. L. Perkins, a friend and former 

 pupil of Mr. Poulton. I worked at the ontogeny of 

 these larvie, with a view to throwing further light, if 

 possible, upon the question of the origin and develop- 

 ment of the red spots which sometimes occur in this 

 species. 



Since the appearance of Professor Weismann's Essay 

 on ' The Origin of the Markings of Caterpillars,' and 

 Professor R. Meldola's notes on it (' Studies in the Theory 



