472 



leaving the more fluid portion in contact with the old cuticula. When 

 the rupture of the old cuticula comes and the fluid is exposed to air 

 it hardens, and cements the appendages to the body. However, if the 

 pupa be put into water or weak alcohol the cementing material is dis- 

 solved, and the appendages are set free, a fact also observed by Gonin 

 and Bugnion. I am ignorant of the nature of this fluid. 



In the pupa most of these cells degenerate, and during the life of 

 the pupa many entirely disappear. A considerable number remain upon 

 the pronotum to secrete enough fluid to start the animal in the final 

 ecdysis. In the breaking down of one of these cells the body of the 

 cell becomes densely granular (Fig. 2), the nucleus exceedingly granu- 

 lar, and the nucleoli(?) are lost (Fig. 4). This continues until the cell 

 body is small, the nuclear membrane lost, and the nucleus a mass of 

 irregular, dense granules (Fig. 5). Soon the cell is detached from the 

 hypodermis, and floats free in the haemolymph, where it is destroyed. 



In Clisiocampa americana^ I have observed the cells which form 

 the hair and secrete the exuvial fluid degenerate to a condition like 

 that shown in Fig. 5, then develop into one of the large scales which 

 cover the body of the imago. 



Summary: The exuvial glands are not true glands, but the seti- 

 gerous cells which, in early life, are chiefly concerned with the forma- 

 tion of the hairs upon the body; but upon the loss of these, the cell 

 takes on the function of secreting the exuvial fluid, which is most 

 copious at pupation. These cells degenerate in the pupa, and take no 

 part in the formation of the imaginai ornamentation. 



Hull Zoological Laboratory. University of Chicago, Chicago, 111., U. S.A. 

 1 Feb. 1902. 



Bibliography. 



1894. Gonin, J., Recherches sur la métamorphose des lépidoptères. De la forma- 

 tion des appendices imaginaux dans la chenille du Pieris hrassicae. Bull. 

 Soc. Vaud. sci. Nat. Vol. XXX. pis. 11—15. p. 89—138. 



1898. Packard, A. S., A Text-Book of Entomology. New York. (XVII, 729 p. 



1898. Bugnion, E., Letter to Packard (1898). p. 613— 615. 



3. Verzeichnis der in der näheren Umgebung von Göttingen gesammelten 



Milben. 



Von Hans Voigts, Oslebshausen (Bremen). 



eingeg. 5. März 1902. 



Ende April bis Anfang Juni vor. Jahres habe ich in der näheren 

 Umgebung von Göttingen (i. Hannover) auf meinen coleopterologischeu 

 Excursionen auch auf die Milben und Collembolen meine Sammel- 

 thätigkeit ausgedehnt, die erfreulicher Weise recht gute Resultate er- 

 geben hat. In liebenswürdiger Weise hat die Bestimmung der Milben 



