May 28, 1897.] 



SCIENCE. 



845 



the individual is in part due will persist in the 

 nest generation ; and, furthermore, that there 

 will arise, by like processes in successive gen- 

 erations, an accumulation of such connate char- 

 acters. Hence, it is said there may appear to 

 be an inheritance of acquired characters where, 

 in reality, there is only an accumulation of con- 

 nate characters identical with the acquired char- 

 acters which, as it were, shield the connate 

 characters while they are accumulating in suc- 

 cessive generations. 



My intention is not to discuss the merits of this 

 hypothesis, but to say that, if I understand it, 

 it is by no means new. It was clearly set forth 

 by Herbert Spencer, in his ' Principles of Bi- 

 ology,' in the year 1866. Though it may have 

 been presented by him or by others before that 

 time, in writings of which I am uninformed, it 

 will be of interest to examine the following 

 statement of it in the work referred to : 



" The working out of the process is here somewhat 

 difficult to follow ; hut it appears to me that as fast 

 as the number of bodily and mental faculties in- 

 creases, and as fast as the maintenance of life comes 

 to depend less on the amount of any one, and more 

 on the combined action of all ; so fast does the pro- 

 duction of specialties of character by natural selec- 

 tion alone, become difficult. Particularly does this 

 seem to be so with a species so multitudinous in its 

 powers as mankind ; and above all does it seem to be 

 so with such of the human powers as have but minor 

 shares in aiding the struggle for life — the esthetic 

 faculties, for example. 



" It by no means follows, however, that in cases of 

 this kind, and cases of the preceding kind natural 

 selection plays no part. Wherever it is not the chief 

 agent in working organic changes, it is still, very 

 generally, a secondary agent. The survival of the 

 fittest must nearly always further the production of 

 modifications which produce fitness ; whether they he 

 modifications that^have arisen incidentally, or modi- 

 fications that have been caused by direct adaptation. 

 Evidently those individuals whose constitutions or 

 circumstances have facilitated the production in them 

 of any structural change consequent on any func- 

 tional change demanded by some new external con- 

 dition, will be the individuals most likely to live and 

 to leave descendants. There must be a natural selec- 

 tion of functionally-acquired peculiarities, as well 

 as of incidental peculiarities ; and hence such struc- 

 tural changes in a species as result from changes of 

 habit necessitated by changed circumstances, natural 



selection will render more rapid than they would 

 otherwise be." (Prin. of Biology, "Vol. 1, p. 454.) 

 Robert M. Pieecb. 

 Philadelphia, Pa. 



euproctis cheysorrhcea in massachusetts. 



On May I3th Dr, Roland Thaxter brought 

 me a few larvse he had found on pear trees in 

 Cambridge. After examination I identified 

 these as Euproctis (Porthesia) chrysorrhcea Linne, 

 commonly called the Goldtail, a species hitherto 

 unrecorded from this country. It occurs locally 

 in England, is abundant in central and southern 

 Europe, and is also recorded from northern 

 Africa and Asia Minor. When found in 

 great profusion their ravages are exceedingly 

 serious. 



May 15th, Dr. Thaxter and I visited a locality 

 in Somerville, not far from the Cambridge line, 

 and found the larvEe extremely abundant on 

 pear, and somewhat less so on apple. We were 

 told that they were noticed last spring for the 

 first time and that they fed only on pear and 

 apple. The larvae feed gregariously and build 

 small, tent-like nests. A slight jar causes them 

 to drop from the trees and they give rise to 

 further annoyance by the urticating power of 

 their hairs. The larva may be described briefly 

 as blackish with ochreous hairs, dorsal line 

 double with pale ochreous, reddish markings, 

 subdorsal line broad, with interrupted white 

 markings ; the tenth and eleventh segments 

 have a conspicuous, dorsal, red tubercule. The 

 head and thorax of the moth are white ; the 

 abdomen is white, with a brown or buff anal 

 tuft ; the wings are pure white, frequently with 

 a black spot on the lower posterior margin of 

 the fore wings. The alar expanse is 32-38 mm. 



As previously stated, they have been found 

 to feed here only on pear and apple, and the at- 

 tempts I have made to effect a change of food 

 have, thus far, failed. Abroad, however, the 

 species has many food plants, apple, pear, 

 plum, hawthorn, bramble, elm, willow, beech, 

 oak, hazel nut, and hornbean being among those 

 recorded. At present the larvse seem to be 

 confined to a rather limited area in Somerville 

 and Cambridge. It is difficult to give an adequate 

 idea of their abundance, their increase since 

 last year, and their destructiveness. If the 



