810 



SCIENCE. 



[N. S. Vol. XXIV. No. 625. 



since 4 say ' sp. 4 ' and 4 say ' sp. 3 ' ; I agree 

 with the latter. In TVa, 7 say 1855, 8 say 

 1880, one says date when synonymy was first 

 recognized: the answer depends on the mean- 

 ing of the word ' removed ' ; if this be taken 

 literally, the answer is ' either 1880 or any 

 previous date when the synonymy may have 

 been recognized ' ; but if we regard the spirit 

 of the question, it will be obvious that when 

 a genus is once established it includes all 

 species congeneric with its genotype whether 

 they have been ' removed ' to it or no — there- 

 fore my answer was 1855. Ambiguity in this 

 question may have been the cause of the 

 equality of votes. In the case of question 

 VI, the pronounced majority is perhaps due 

 to ambiguity in the answer: what I say is 

 that the reviser can not select as genotype of 

 an early genus any species that is already 

 genotype of a subsequent genus, so long as 

 there remains any species free among the orig- 

 inally included species; therefore I wrote 

 ' yes ' to the first clause of the question, and 

 ' no ' to its second clause. 



Adding my replies to those given, it appears 

 that I agree with the majority, usually a large 

 •absolute majority, in twelve out of the thir- 

 teen cases, and that the thirteenth case, which 

 is ambiguous, is a draw. After this Mr. 

 Stone will probably admit that the method is 

 understood by me, and he will perhaps accept 

 my assurance that I am only an insignificant 

 unit among a fairly large number of old- 

 world writers of similar views and all provided 

 with the small amount of intelligence re- 

 quired. 



The considerable agreement attained by 

 those who have answered his questions should 

 prevent the wholesale condemnation of the 

 elimination method; but it would add interest 

 to the figures if we were told whether the 

 minority was generally composed of the same 

 writers. If so, they would probably yield 

 only to force majeure; but if not, they might 

 be brought into line by gentle argument. 



Mr. Stone makes out a very strong case for 



the * first species ' method ; but is he correct 



in saying that it ' can lead to but one result ' ? 



Would he kindly refer to Annals and Mag. 



Nat. Hist. (2), XVI., pp. 95, 96, and say 



what, on that method, is the genotype of 

 Hemipedina? F. A. Bather. 



London, England, 

 November 12, 1906. 



SPECIAL ARTICLES. 

 POLYEMBRYONY AND THE FIXING OF SEX. 



Naturalists have long been familiar with 

 certain curious and unexplained phenomena 

 connected with the life histories of certain 

 parasitic hymenopterous insects of the fam- 

 ily Chalcididse. DeGeer in 1752 figured a 

 minute black species with dirty-white wings,^ 

 which he reared from minute cocoons attached 

 together side by side in the larva of one of 

 the pear-leaf miners. Westwood, in the sec- 

 ond volume of his Introduction, says of this 

 insect : " The figure has somewhat the air of 

 Encyrtus; but the pupae are naked in that 

 genus." 



In the American Naturalist for February, 

 1882, in the second installment of an article 

 entitled ' On some Curious Methods of Pupa- 

 tion among the Chalcididse,' the writer de- 

 scribed a precisely similar object found in the 

 mines of an oak-leaf miner, Lithocolletis fitch- 

 ella, at Washington and bred from it a num- 

 ber of specimens of an encyrtid of the genus 

 Copidosoma. He further described somewhat 

 similar cocoon-like formations within the lar- 

 val skin of the pine-leaf miner, Gelechia pini- 

 foliella; also in the skin of the larva of the 

 twig borer, Anarsia lineatella, in the larva 

 val skin of the pine-leaf miner, Gelechia pini- 

 solidaginis) , and finally described at some 

 length the strange habits of a congeneric para- 

 site which attacks the larva of Plusia hras- 

 sicce. The latter was described as follows: 



The Plusia larva, up to the time of commencing 

 to spin, appeared quite healthy, although perhaps 

 a little sluggish. Then suddenly its torpor in- 

 creased, and through the semitransparent skin 

 were seen hundreds of small white parasitic 

 larvae. In two days at the most the host was 

 dead, having perhaps partially finished its cocoon, 

 while its entire body was completely packed with 

 the parasitic larvae or pupae, each surrounded by a 

 cocoon-like cell. A cross-section of the host at 

 this stage showed a regular honeycombed struc- 

 ture. After remaining in the pupal state not 

 longer than twenty days, the chalcidids com- 



