412 NOTES AND MEMORANDA. 



began to disappear, and the pain under the arm sensibly diminished. 

 The affected area on the hand began to perspire considerably, and the 

 pain in the injected spot was as violent as ever, burning horribly like 

 a scald. At 1 the arm])it pain had nearly ceased, the rash had dis- 

 apjieared, but the pain in the hand was so bad that he could hardly 

 bear it. Boring a hole with a red-hot iron came nearest to the effect 

 in his imagination. At 5, 6, 8.30, and 10, there was diminished pain, 

 though at 1 . 30 a.m. he awoke with it. Next day it was gone, but the 

 soreness not until the day after. The marks of the points of the 

 thirty-six spines were still visible when he wrote (16th March). 



Abortion of the Hairs on the Legs of certain Caddis-flies, Ac- 

 Mr. C. Darwin, writing to ' Nature,' says * that several of the facts 

 given in the following letter from Fritz Miiller, aj^pear to him very 

 interesting. Many persons have felt much perplexed about the steps 

 or means by which structures rendered useless under cliangcd condi- 

 tions of life, at first become reduced, and finally quite disaj^pear. A 

 more striking case of such disappearance has never been published. 

 Several years ago some valuable letters on this subject by Mr. 

 Romanes (together with one by himself) were inserted in the columns 

 of ' Nature.' Since then various facts have often led him to speculate 

 on the existence of some inherent tendency in every part of every 

 organism to be gradually reduced and to disappear, unless in some 

 manner prevented. But beyond this vague speculation he could 

 never clearly see his way. As far, therefore, as he can judge, the 

 explanation suggested by Fritz Miiller well deserves the careful con- 

 sideration of all those who are interested on such points, and may 

 prove of widely extended application. Hardly anyone who has con- 

 sidered such cases as those of the stripes which occasionally ajipear on 

 the legs and even bodies of horses and apes — or of the development of 

 certain muscles in man which are not proper to him, but are common 

 in the Quadrumana — or again, of some peloric fiowers — will doubt 

 that characters lost for an almost endless number of generations, may 

 suddenly reappear. In the case of natural species we are so much 

 accustomed to apply the term reversion or atavism to the reappearance 

 of a lost part, that we are liable to forget that its disappearance may be 

 equally due to this same cause. 



In the letter (written from Brazil), Fritz Miiller says that there is 

 there a locality in which a peculiar fauna lives, viz, the rocks of 

 waterfalls, which are of very frequent occurrence. On these rocks, 

 along which the water is slowly trickling down, or which are continually 

 wetted by the spray of the waterfall, there live various beetles not 

 to be met with anywhere else, larvae of diptera and caddis-flies. 



The pupae of these caddis-flies, as well as those ^ living in 

 Bromelife, are distinguished by a very interesting feature. In other 

 caddis-flies the feet of the second pair of legs (and in some species 

 those of the first pair also) are fringed in the pupje with long hairs, 

 which serve the pupa, after leaving its case, to swim to the surface 

 of the water for its final transformation. Now neither on the surface 

 of bare or moss-covered rocks, nor in the narrow space between the 

 * 'Nature,' sis. (1879) 462. 



