292 Herr J. Wagner on the 



present is a convenient opportunity to si)eak of the provisional 

 organ of the aquatic and certain land- mites, wliich is regarded 

 by Henking (No. 20) as a " primitive trachea '' (' Ur- 

 trachee'), while Kramer (No. 36) considers it to be a "sus- 

 pensory apparatus " (" Suspensionsapparat ") for the embryos. 

 Henking's view appears to me to be unfounded, since he did 

 not see an actual trachea, penetrating from the organ in 

 question into the body. This paired embryonic organ, which 

 1 did not succeed in observing in Ixodes, and other observers 

 failed to find in many other forms, merits special attention, 

 since both in its position on each side of the body in the 

 neighbourhood of one of the anterior pairs of thoracic limbs, 

 as well as in its shape, with narrow base and swollen tip, it 

 recalls the embryonic organ lately described by Vejdovsky 

 (No. 65) in Chernes. The author in question is of the 

 opinion that, from comparison with Cyphophthahnus duri- 

 cornisy Joseph (No. 22), this organ, which Avas noticed neither 

 by Metschnikoff (No. 44) nor by Barrois (No. 2) in Cheltfer, 

 may be compared with rudimentary stalked eyes {loc. cit. 

 p. 130). It seems to me that this assumption is ill-founded, 

 since the structure of the organ is but little suggestive of that 

 of an eye ; and, besides, the stalked eyes of Gyphophthalmus 

 — a form widely distant from the Pseudoscorpioninee, and at 

 any rate ill-studied — or more correctly the eyes seated upon 

 lateral processes of the body, might have arisen as a secondary 

 character in the species itself, as, for instance, the stalked 

 eyes of certain Ephemeridee among the Insects have been 

 developed. 



In tlie same way it is possible to institute a comparison 

 with the lateral organs of the Solifugge (Croneberg, No. 12), 

 perhaps also with those of the Phalangidte (Faussek, No. 14), 

 and finally with the provisional organs situated in Thely- 

 'pJionus and in Phrynus at the base of the second pair of legs 

 (iStrubell, No. 63). 



Before proceeding to state the views of those specialists 

 who would derive the Tracheata from an ancestral form, I 

 would like to refer to the so-called Malpighian tubes. Since 

 the homology of these organs in all Tracheata is recognized, 

 it is assumed that their origin and also their function is 

 similar ; their importance chiefly consists in the fact that they 

 are present in all fully-developed Tracheata, but are absent 

 in the Branchiata. This, at any rate, is the view represented 

 in the text-books of Lang and von Kennel. 



As regards their origin, according to my own observations 

 the Malpighian tubes develop in the case of Ixodes (and 

 probably in the Acarina in general) from the endoderm. As 



