PSYCHE. 



THE PRIMITIVE NUMBER OF MALPIGHIAN VESSELS IX 



INSECTS.— II. 



BY WILLIAM MORTON WHEELER, PH.D., CHICAGO, ILL. 



Apterygota. In searching for the 

 ancestral conditions of the Malpighian 

 vessels it is natural to turn first to this 

 group. The few data are, however, 

 very unsatisfactory on account of the 

 wide differences between the statements 

 of authors. As an example we may 

 take Lepisma. According to Ram- 

 dohr* this insect has two Malpighian 

 vessels ; according to Treviranus, f 

 Rovelli,]: Gegenbaur§ and v. Siebold, || 

 four ; according to Leuckart,^[ six ; ac- 

 cording to Schindler,** eight. Fernald 

 saysff that he was unable to ascertain 



*Abhandlung ueber die verdauungs werkzeuge der 

 insecten. Halle, 1S11. ■ 



t Vermichte schriften Bd. ii heft, i, p. 15. Gottingen, 

 1816. 



t Alcune richerche sul tubo digerente degli atteri, 

 ortotteri e pseudo-neurotteri. Come, 1SS4. 



§ Grundriss, etc., 1S74, p. 292. 



|| Anatomie d. wirbellosen, p. 625. 



IT Frey u. Leuckart, Anatomie u. physiologie d. wir- 

 bellosen, p. 102. 



** Beitrage zur kenntniss der Malpighi'schen getasse 

 der insecten. Zeitschr. f. wiss. zool. Bd. 30, 1S7S, p. 

 602. 



ft The relationships of arthropods. Studies biol. lab. 

 Johns Hopkins univ. vol. iv, no. 7, 1S90, p. 46+. 



the number, but feels certain that there 

 are at least four. 



In Machilis Grassi* found twelve 

 Malpighian vessels, uniting in pairs and 

 hence "on peut les considerer comme 

 etant au nombre de six." But Oude- 

 manns,f who has studied the anatomy 

 of Machilis very carefully, finds twenty 

 vessels, uniting in pairs and opening by 

 means of ten apertures at the junction 

 of the mid and hind-guts. 



Campodea has about 16 Malpighian 

 vessels according to Grassi. j These 

 organs were seen by Oudemanns§ but 

 he failed to ascertain their exact 

 number. 



According to Grassi |j both Nicoletia 

 and Lepismina have six Malpighian 

 vessels, opening separately into the hind- 

 gut. 



*Les ancetres des myriapodes et des insectes, tome 

 xi, 1SS9, p. 310. 



t Bijdrage tot de kennis der Thysanura en Collem- 

 bola, Amsterdam, 1SS7, p- 66. 



\loco citato, p. 310. 



§1. c. p. 67. 



II 1. c. p. 311. 



