Decembek 19, 1913] 



SCIENCE 



883 



my note^ regarding the possible origin of 

 mutations in somatic cells, in which I er- 

 roneously credited to Davis- the suggestion 

 that triploid (sem-gigas) mutants of (Eno- 

 thera are to be accounted for through the pro- 

 duction of occasional diploid gametes by an 

 extra fission of chromosomes. Obviously, as 

 Gates points out, Davis's suggestion of dip- 

 loid gametes could not have been offered as 

 an explanation of triploid mutants, for the 

 reason that the triploid condition in (Eno- 

 thera was not known in 1911. Davis's sug- 

 gestion was offered to account for the tetra- 

 ploid condition of gigas mutants. The sug- 

 gestion that tetraploid mutants may arise 

 through a double fission of chromosomes in 

 some mitosis soon after fertilization should 

 have been credited to Gates.' I am grateful 

 to Gates for setting me right in these matters. 

 E. A. Emerson 

 University of Nebraska 



how oryctes rhinoceros, a dynastid beetle, 

 uses its horn 



Many beetles, particularly in the family 

 Dynastidaj, have more or less conspicuous 

 horns or processes on their head or prothorax. 

 These often assume fantastic shapes and enor- 

 mous proportions. Sometimes they occur on 

 both sexes, but more often they are found only 

 on the male or at least reach their greatest 

 development there. In the latter case they 

 have been looked upon by some as characters 

 that may have been developed through sexual 

 selection, the assumption being that males so 

 ornamented were more attractive to the 

 females or in some other way were more likely 

 to be able to mate and thus perpetuate their 

 kind. While such a theory may not be very 

 satisfactory without more detailed observations 

 or experiments to prove its soundness, we 

 know of no other that is any more acceptable. 



Many of the horns and projections are of 

 such a size and character that it is hard to 

 conceive of their being of any possible use to 

 the insect in its struggle for food, or with its 



lAmer. Nat., 47: 375, 1913. 



2 Annals of Botany, 25: 959, 1911. 



sArcMv f. Zellforsch., 3: 525, 1909. 



enemies. Possibly some of them are of no use 

 in this way, but while studying the rhinoceros 

 beetles, Oryctes rhinoceros, in Samoa last sum- 

 mer, I had an opportunity to watch these 

 insects making a very evident and profitable 

 use of the horn on their heads. The horn is 

 present on both sexes and is usually longer on 

 the male than on the female, but many males 

 may be found with very short horns and many 

 females with long horns, so that the sexes can 

 not be separated by this character. The horns 

 vary in length from 1.5 mm. to 10 mm., 6 or 7 

 mm. being about the average length. The 

 beetles feed on the growing heart in the crown 

 of the coconut trees. They usually enter the 

 trees close to the base of a leaf, crawling down 

 as far as they can between the tree and leaf- 

 stem before beginning to bore. The spiny legs 

 enable the beetle to brace itself firmly before it 

 begins literally to root its way into the web- 

 like sheath through which it usually has to 

 pass before it reaches the hard wood. In doing 

 this the head is lowered and the horn thus 

 thrust forward. The horn becomes imbedded 

 in the tissue of the plant and when it is raised 

 serves as an anchor to hold the insect while it 

 pulls or pushes its body forward with its legs, 

 or while it tears the tissue of the plant with its 

 heavy mandibles. The insect will always root 

 and push its way as deep as it can before it 

 begins to bore. The amount of power it can 

 develop while trying to force its way between 

 the bases of two leaves or in other tight places 

 is truly remarkable. 



Thus, in this instance at least, we see that 

 this horn is of direct use in aiding the insect 

 to reach its food. 



E. W. DOANE 



Stanford University, 

 September, 1913 



SCIENCE AND THE NEWSPAPER 



While recently giving a discussion of the 

 inclined plane, an idea which was new to me 

 suddenly presented itself. The equation as- 

 serts that the force required to make a mass 

 slide up the plane would under certain condi- 

 tions be made less, by making the plane 



