and Laboratory Methods. 1647 



A Hint for the Preparation of Internal Organs of Dried Insects. 



Some five years ago attention was directed by Dr. F. Ris to the phylogenetic 

 data afforded by a study of the gizzard-armature of nymph and imago of the 

 same species of Dragonfly (Odonata). Dr. Ris worked on alcoholic material, so 

 that the range of his study was limited chiefly to European species. It may be 

 of interest to readers of the Journal to learn that dried specimens may be 

 employed for dissection and study of this and other internal organs. 



In Odonate imagos, the gizzard lies within the abdomen, in any segment 

 from the third to the seventh. If the entire abdomen be cut from the rest of 

 the body at the base of the third segment, soaked in 70 per cent, alcohol for 

 twenty-four hours or longer, until thoroughly softened, and slit open along one 

 of the membranous pleura, the alimentary canal may be removed, the gizzard 

 opened lengthwise [and its muscular coat removed with fine needles. Its 

 chitinous lining, armed with teeth, may be cleaned and mounted in balsam. 

 This method has been employed with much success by Miss H. T. Higgins, 

 working under my directions, as her recently published results show.* With a 

 little care, we were able to remove the gizzard from a pinned individual, dry 

 the abdomen and restore it to its proper owner without impairing the usefulness 

 of the latter as an ordinary museum specimen. 



A further step may now be indicated. It is, that since some time elapses 

 after metamorphosis before the imago ejects, through its vent, the moulted 

 nymphal lining of its own intestine, so-called teneral imagos, with colors still 

 pale and immature, may yield both nymphal and imaginal gizzard-armatures by 

 use of the same method. This is an important gain, since it furnishes a means 

 of obtaining knowledge of the gizzard of the unknown nymphs of various exotic 

 groups, of which dried imagos are more or less common. 

 University of Pennsylvania, Philadelphia. Philip P. CalVERT. 



Observing the Circulation of the Blood. — Mr. F. J. Medina of Corinto, 

 Nicaragua, has observed that the embryo of a small fish that swarms in the lake 

 of Managua of that country, offers a most excellent means for studying the cir- 

 culation of the blood in living animals. The fish lays its eggs on weeds and 

 roots of plants growing along the lake shores, toward the beginning of the dry 

 season, from November to March. The eggs, being very numerous and laid on 

 different days, supply embryos in different stages of development, thus furnish- 

 ing a wide range for observation. " The eye catches at a glance a beautiful 

 sight of the whole circulatory system, and follows with delighted attention the 

 stream of blood starting from the heart, running in the arteries and veins, and 

 returning to the heart, whose beatings are conspicuously seen. The elongated 

 globules of the blood are distinctly seen, forming inside the blood vessels 

 something like a string of beans. "^ — Sci. Am. 86 : 2. 



* Proceedings, Acad. Nat. Sciences, Phila., 1901, p. 1 26-141, pis. ii-iv. 



