366 The University Science Bulletin. 



were used upon that material which was imbedded for sectioning. 

 Borax carmine and Delafield's hemotoxylin seemed to give the best 

 results. 



The Malpighian tubules of Phlegethontius sexta are six in number 

 and of a light yellowish color. Four of these are located largely 

 laterodorsally to the intestinal tract, the other two being ventrally 

 situated. Each tubule is apparently free at the end distad from the 

 bladder. There are two bladders, located one on each side between 

 the ventriculus and the small intestine (fig. 2), and just posterior to 

 the ventriculus they empty separately into the small intestine 

 through short, smooth tubes (fig. 3). From the opposite end of 

 either bladder a tube arises which runs, dorsally and branches im- 

 mediately into two; one of these tubes runs ventrally and forward, 

 the other dorsally, and this one divides into two more as it nears 

 the top of the ventriculus. These six tubes run forward toward the 

 head and turn back posteriorly at about the second abdominal seg- 

 ment, as shown in figures 5 and 6. Posterior to the bladders all 

 these tubes interweave with the adipose tissue until they lose their 

 identity. 



On high magnification the tubes present an interesting appear- 

 ance, in that each one is covered with small nodules. These nodules 

 become more numerous on the tubes the greater the distance from 

 the connection with the bladder, until at the distal ends the nodules 

 are very closely crowded together (figs. 7 and 8). Tracheae run to 

 the tubes and branch into invisible threads upon the surface of the 

 nodules (fig. 9). 



Both the nodules and the tubes are hollow, and an opening from 

 each nodule leads into the tube, making a continuous cavity to all 

 parts (figs. 10, 11 and 12). The exact histological nature of the 

 tubes is very hard to determine on account of their delicate nature. 

 The figures showing these structures are not shown here, for more 

 work is being done upon them and a later paper will appear. 



LITERATURE. 



Berlese, Antonio. 1909. Gli Inset ti lore organizzazione, sviluppo, abitudini 

 e rapporti coll'uomo, pp. 779-788; figs. 971, 972, 975. Societa Editrice Li- 

 braria, Milano. 



FoLSOM, J. W. 1906. Entomology, with Special Reference to its Biological 

 and Economic Aspects, pp. 123-124. Philadelphia; P. Blakistons & Co. 



Peterson, Alvah. 1912. Anatomy of the Tomato Larva, Protoparce Carolina. 

 Annals of the Entomological Society of America, pp. 245-272; pis. XIX- 

 XXI. Columbus, O. 



