ZOOLOGY. 493 



The causes of " the admirable economic superiority" are analyzed and 

 the author summarizes them as follows : 



(1) "There are a number of chemical rays in this light, as may be 

 shown by photography, but there is only a small proportion of them ; 

 the result must be ascribed to the existence of a fluorescent substance, 

 which has been discovered in the blood of Pyrophorus, and which, by 

 penetrating into the organ, gives it the special and brilliant character 

 which distinguishes the light. The greater number of the chemical 

 rays are trausfcrmed into very brilliant fluorescent rays of a medium 

 wave length." 



(2) " Optic analysis shows that the light is in great part composed of 

 rays similar to those which are found at those points of the spectrum 

 where experience has fixed the maximum of illuminating intensity." 



(3) "There is no loss by heat radiation; the amount of heat given 

 off, even at the time of greatest activity, is infinitesimal." 



(4) "There is no reason for supposing that there is any conversion 

 of energy into electricity." 



(5) " This marvellous light is physiological because it is of vital origin, 

 and because no other source is as well adapted to the wants of the 

 organ of vision in the animal series." (Bull, Soc. Zool. France, xi, 

 pp. 1-275, 9 pi.; J. R. M. S. (2), vi, pp. 595-597.) 



Odoriferous apparatus of the bed-bug. — A large section ot insects of 

 the great order of Hemiptera are notorious for the unpleasant odors 

 which emanate from their bodies, and not the least notorious is the form 

 too well known to many under the name of bed-bug. The allies of the 

 bed-bug have mostly wings. In the early or larval condition they have 

 three abdominal and dorsal glands, and these persist until the last 

 change of skin; they then become atrophied; when their wings appear, 

 a thoracic and sternal glandular apparatus becomes developed. Those 

 species " which suck sap are therefore provided with two systems of 

 organs of secretion, situated in two opposite parts of the body, accord- 

 ing as they are in the state of larva or pupa, or in the adult state." 



" The presence, at different ages," says Mr. Kiinckel, " in the same 

 insect, of glands having different anatomical relations, but possessing 

 the same physiological attributes, is a fact which leads us to interesting 

 deductions." We need not follow Mr. Kiinckel in these deductions, but 

 simply record his observations on the bed bug. " Some naturalists," 

 he remarks, " have thought that these creatures, when adult, repre- 

 sented the pupa state of other Hemiptera, and that the number of moults 

 justified their opinion ;" but according to Mr. Kiinckel, " the disappear- 

 ance of the larval and pupal odoriferous glands coincides with the ap- 

 pearance of new odoriferous glands, the exclusive appanage of the adult 

 Hemiptera; then the Cimices capable of reproduction and regarded as 

 pupai are not able after another moult to acquire wings ; they are creat- 

 ures which have attained the last term of their development." In fine, 



