210 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



G. coleoptratorum, G. stahularis, and Trachynotus inermis ; in the last 

 of these paedogenesis is especially well marked. 



Trombidium fuliginosum.* — H. Henking, after stating his belief 

 that Pagenstecher, in his well-known monograph, was dealing with 

 this species, and not with T. liolosericeum, describes the saccular glands 

 in the last joints of the legs which afford a secretion which appears 

 to enable the animal to move on upright smooth surfaces. After 

 describing the tracheal system and the air-chambers connected there- 

 with, the structure of the sucking apparatus, and the bi-lobed nature 

 of the " liver-stomach " are pointed out, and the presence of large club- 

 shaped cells in the walls of the latter described ; some of these, in 

 addition to their granulated protoplasm, have a more or less large 

 number of dark granules, which are most numerous at the free end ; 

 as they increase, the tip of the cell becomes sharply separated off from 

 the clearer part of the cell, undergoes constriction, and becomes com- 

 pletely distinct, falling into the cavity of the stomach. Around this 

 organ the cells of the fat-body are regularly arranged. 



In the nymph and in the prosopon we find in the middle line and in 

 the anterior dorsal region, close to the eyes, a chitinous structure 

 containing three spaces ; these are the protective chambers of a 

 sensory organ. The structure of these parts is described, but no 

 opinion is offered as to their function. The legs are provided with 

 tactile setae, which are especially well developed in their terminal 

 joints, and are connected with a large tactile ganglion ; a tactile 

 ganglion is also found in the terminal joint of the maxillary palp. 



The author is of opinion that Pagenstecher has mistaken the sexes, 

 and that what he took for males are females, and the females males. 

 The spermatozoa are oval, plano-convex bodies, without any tail, and 

 appear to move by means of a membrane. The structure of the male 

 organs is described, attention being directed to the complicated 

 chitinous penis, and the vacuolated cylindrical cells found in the tube 

 which opens at the root of that organ. 



A new nomenclature is suggested for the various stages of the 

 complicated life-history of these forms ; the egg-like stage from 

 which the nymph is developed, is called the nymphochrysalis, that 

 from which the perfect animal is formed the teleiocliry sails ; the egg- 

 membrane, called by Claparede the " Zwischenhaut," is denominated 

 the " apoderma." When this last appears, the Acarus passes into the 

 SchadonopJian-st&ge (cr;;^a8coi/ = larva), the nymphophan-stage, or the 

 teleiophan-stage. When the apoderma disappears the separate forms 

 become respectively larva, nymph, or prosopon (adult). It may be con- 

 venient to give the diagram by which the author illustrates these stages. 



Quiescent Stages. g | Free-living Stages. 



1. Egg. rt ("Schadonophan-stage. 'o,^ I Larva. 



I i I sa( I 



2. Nymphochrysalis. t3 <Nymphophan-stage. ^<1 



I ^1 



,3. Teleiochrysalis. "^ vTeleiophan-stage. 



Nymph. 



I 

 (^ Prosopon. 



* Zeitschr. f. Wiss. Zool., xxxvii. (1882) pp. 553-663 (3 pis.). 



