466 



SCIENCE 



[N. S. Vol. XLVI. No. 1193 



ten weeks. It was found difficult to carry defi- 

 nite specific larvre under observation in 

 Petri dishes through the entire period, but the 

 time was established by noting the appearance 

 of new groups of moths in the larger stock of 

 fur. Just what there was in the Petri-dish 

 method of culture to hinder the larval develop- 

 ment could not be determined. Some larvse 

 grew to large size, approximating maturity, 

 others died in a few weeks, but none were cer- 

 tainly carried from the egg to the cocoon. 

 Ten weeks appeared to be the shortest period 

 in which larval growth was completed, but this 

 is necessarily partly an estimate. 



The cocoon stage lasted at the shortest two 

 weeks. This was definitely established by ob- 

 serving the time at which larvse ceased feeding, 

 and closed their cases, and then putting such 

 cases away for observation. 



It is probable that all stages of the life his- 

 tory may ujider some circumstances be more 

 or less indefinitely lengthened. Certainly the 

 larval stage may. Its conclusion probably de- 

 pends entirely on the obtaining of a sufficient 

 amount of food, and may probably last several 

 months, as over winter for example. Winter 

 stops the activities of this moth only when the 

 temperature of the surroundings is too much 

 lowered. In the present investigation moths 

 were observed emerging from cocoons and 

 larvce were seen feeding during all months of 

 the year. Breeding experiments were not at- 

 tempted during the winter but there seems no 

 reason to suppose they would not have been 

 successful and that egg-laying would also have 

 occurred. 



Remedies for Moths. — A summary of results 

 along this line may be interesting. 



Remedies intended for the flying-moth stage 

 are worse than useless. So-called repellants 

 such as tobacco, cedar, did not repel or harm 

 the moth in any stage. The imago stage is the 

 most delicate of all, but it could be placed in a 

 small closed tmnbler with burning tobacco with 

 no apparent injury. Cloth soaked in odorifer- 

 ous substances for the purpose of repelling 

 them was made the recipient of eggs as read- 

 ily as untreated cloth. As already noted, the 

 moth laid eggs as readily on cotton and silk as 



on wool although neither of these was used as 

 food by the larvje. 



Any method of attack must be directed 

 toward the larval stage to be effective. 

 Camphor and napthalene in closed places kill 

 all stages. The egg and larvse turn from whit- 

 ish to a yellowish brown in color; the larvse 

 cease activity almost immediately. No gaseous 

 poisons were tried but undoubtedly the com.- 

 mon ones would be effective. Kerosene and 

 gasoline fumes were not effective. 



The main method of attack in this case was 

 directed toward poisoning the larras through 

 their food. The problem was to find some poi- 

 son which could be placed on cloth and serve 

 to kiU larvse feeding on it before they could 

 do material damage. At the same time it must 

 not be harmful to human beings, or if harmful 

 in posse, must be insoluble. If baby wants to 

 chew mother's dress or its woolen blanket, it 

 must be able to do so with impimity. After 

 about four years of nearly continuous investi- 

 gation, during which several chemists were 

 cooperating, the problem was finally dropped. 

 Numerous compounds were used in tests but 

 the larvse proved singularly immune. Larvae 

 placed in Petri dishes with a piece of cloth 

 soaked in corrosive sublimate as well as other 

 common poisons, ate of the cloth as shown by 

 the color of their alimentary canal and the 

 fseces, but lived on for weeks apparently unin- 

 jured. Some few substances were found which 

 did appear to have some result but not enough 

 to justify adopting them as the basis of a moth- 

 proofing process. 



The problem still seems to be possible, but 

 the solution is not apparent. After the sub- 

 stance is found, there still remains the over- 

 coming of the objections of the tailors and 

 clothing manufacturers, some of whom con- 

 sider clothes moths among their best friends. 



Ealph C. Benedict 

 Brooklyn 



a chromosome difference correlated 

 with sex differences in 



SPH.ffiROCARPOS 



The chromosome group found in the cells 

 of the female gametophyte of Sphwrocarpos 

 Donnellii contains one large element which 



