372 



The Journal of Heredity 



the candle power of the j^low at 

 1/50,000 and that of the flash at 1/400. 

 Althouj^h this seems a small amount, in 

 comparison with the size of the insect 

 it is truly surprising. 



There are practically no invisible 

 rays in the firefly's \\p,hi, and hence no 

 heat and a remarkable efficiency. The 

 efficiency of Photinus has been rated 

 from 90^' c to 96.5' (' , while the efficiency 

 of a carbon j^low lamj) is but OA^/c, and 

 the most efficient form of artificial 

 illuminants produced by man are but 

 4% efficient. Nothing is known about 

 the energy input of the insect, but the 

 resulting fight is the most efficient 

 known to science. To supply an eciual 

 amount of light from the same illumi- 

 nated area in the laboratory would re- 

 quire a temperature of 2,000° F. 



If the insect is forced by stimulation 

 to keep flashing continuously, life soon 

 becomes extinct, apparently from ex- 

 haustion. This indicates that the en- 

 ergy in])ut is considerable on the part 

 of the insect; it is also possible that 

 there may be some reservoir of storcd-up 

 light energy which cannot be rc])l(nishcd 

 indefinitely. 



There is apparently abs(;lutcly no 

 radiation of heat during the flashing. 

 as measured bv the most accurate 



means obtainable, which practically 

 preclude the possibility of error. No 

 infra-red rays are thrown off, for if there 

 were, the insect would soon be dessicated 

 by its own heat. The body tempera- 

 ture of the photogenic segments is 

 higher, however, than the temperature 

 of other parts of the body. 



Popular opinion frequently to the 

 contrary, the fight of the firefly is 

 connected in no way with any "phos- 

 phoresence" or "X-rays." It seems 

 most probable that it is the result of the 

 presence of moisture, oxygen and some 

 unknown substance, possibly a fat or an 

 albuminoid, together with some form of 

 oxidation taking place. Unless some 

 startling and heretofore undiscovered 

 cndo-thermic action is going on whereby 

 light is emitted, there seems to be no 

 other possible explanation of the fluor- 

 esence. Some observers have suggested 

 phosphuretted hydrogen or carbon to 

 be oxidized, while some think the fight 

 to be the result of the breaking down 

 of some nitrogenous substance to form 

 crystalfine urates. Every opinion is 

 backed by some evidence, but none is 

 based upon sufficient grounds to make it 

 entirely ]jlausible from every point of 

 view, so that the whole m.atter is still 

 as much in doubt as ever. 



The Psychology of Special Abilities and Disabilities 



THE PSYCHOLOGY OF SPECIAL ABILI- 

 TIES AND DISABILITIES, by Augusta F. 

 Bronncr, Assistant Director of the Juvenile 

 Psychopathic Institute, Chicago. Pp. 269. 

 Price, $1.75. Boston: Little, Brown & Co., 

 1917. 



Psychologists as well as eugenists have 

 lately been emphasizing the fact that 

 no two children are alike, but the schools 

 have found it difficult to act on this 

 fact. Dr. Bronner's book presents the 

 problem of individual differences clearly 

 and strikingly. She describes many 

 detailed cases, and discusses the general 

 principles involved, where a subnormal 

 child has special ability in some ])ar- 

 ticular line, and deals more shortly 

 with children who are normal in most 

 ways but in whom some one mental 



function may be defective. The book 

 is so simply written that it will appeal 

 to parents and teachers, as well as to 

 specialists; but the former should be 

 warned that they may easily get a 

 false idea of individual differences, 

 becavise of the emphasis which Dr. 

 Bronner lays on extreme cases. As a 

 fact, good qualities usually go together, 

 and bad qvialities usually go together. 

 A child who is deficient in several 

 mental functions is more likely than 

 the average to be deficient in all mental 

 functions. Intelligence tends to form 

 a level, instead of a system of peaks 

 and valleys, but an unguardeel consider- 

 ation of the selected cases Dr. Bronner 

 presents might lead the reader to think 

 the reverse is the case. 



