SS ENTOMOLOGICAL NEWS. , [Jan., '03 



Entomologica.1 Literatuire. 



Ricerche suU' apparato di secrezione e sul secreto della Coccinella 

 7 punctata L. Pel Dott. Antonio Porta. Con una tavola. Anato- 

 mischer Anzeiger, Jena, Oct. 24, 1902. Pp. 177-193. — In this paper Dr. 

 Porta presents the results of a study of the nature, physiological action 

 and source of the yellow secretion emitted by this Coccinella, when 

 irritated, in both larval and adult stages. They disagree so much from 

 previous ideas as to be worth noticing here. The secretion escapes by a 

 fissure at the apex of each femur in the adul: (as previously known), and 

 by pairs of openings at some of the intersegmental abdominal articula- 

 tions of the larva ; it is orange-yellow in color, astringent and disgusting 

 in taste, has a fresh pea odor ; is soluble in distilled water, absolute alco- 

 hol and ammonia ; insoluble in acetic ether, acetic acid, sulphuric ether, 

 and chloroform ; has a very sensible acid reaction ; responds to Petten- 

 kofer's test for bile acids, but not to Giinzbe; g's or Boas' tests for hydro- 

 chloric acid, or to Gmelin's test for bile pigments ; spectroscopically ex- 

 amined, it is described as approaching urobilin ; microscopically studied, 

 it contains numerous globules, granular and homogeneous bodies of vari- 

 ous sizes and shapes, evidently on the way to dissolution. The weight 

 of the secretion of one individual was determined by placing the beetle 

 on filter paper, stimulating it, preferably by an electro-magnetic machine, 

 and weighing the paper before and after ; this precaution was necessary, 

 as the liquid quickly evaporates. From a number of experiments the 

 average weight of the secretion is given as .0026 gram. To obtain the 

 secretion in solution in large quantities, a number of Coccinellae (90-500) 

 were placed in a definite quantity of water ; the coldness of the latter, 

 together with mechanical irritation by a forceps, caused a flow of the 

 secretion. Hypodermic injections of such solutions always produced 

 paralysis in frogs, tritons, guinea-pigs and rabbits, followed in some cases 

 by death. Paralysis or death was proven, by appropriately arranged ex- 

 periments, to be due to the effect of the venom on the medulla oblongata, 

 not on the spinal cord nor on the heart, the latter in frogs continuing to 

 pulsate after death. Relatively strong hypodermic injections into other 

 insects produced temporary immobility but not death ; living insects con- 

 fined with living Coccinella? were not affected sensibly, although there 

 were numerous yellow stains on the box showing that the secretion had 

 been emitted. It is hardly necessary to say that the quantities of secre- 

 tion injected were greatly in excess of that produced by a single Coccin- 

 ella. Coccinellae offered to and swallowed by frogs were soon vomited. 



As to the source of this secretion, and this is the most novel of his 

 results, Dr. Porta completely disagrees with Leydig and others who as- 

 serted the secretion to be ejected blood. Finding that the mid-intestine 

 likewise responds to Pettenkofer's test, he believes that the follicles situ, 

 ated in the meshes of a network of connective tissue between the muscle- 



