INTERNAL ANATOMY OF THE GAMASIN^E. 287 



up to absolute, before imbedding. Latterly, in numerous cases, the picro-sulpburic acid 

 has been omitted, and the creature passed direct from boiling water to dilute alcohol, 

 I think with advantage. 



Both dissections and sections have been stained either with picro-carmine, borax 

 carmine, or hsenaatoxylin. 



The observations on living specimens have been made by the aid of the cells I have 

 usually employed in rearing and observing Acarina, viz. glass rings cemented to ordinary 

 3x1 in. microscopical glass slips and covered by another similar slip which is kept on 

 by two elastic bands or a clip ; tbe bottom of the cell tbus formed is covered with moist 

 blotting-paper, and the whole apparatus is placed on the horizontal stage of a Stephenson 

 microscope for observation. 



The Species used. 



A number of species have been examined of which no record appears in this paper, 

 because I did not find them vary sufficiently from Winkler's type to render it necessary 

 to mention them. 



In selecting the species of those that departed far enough from that type I have 

 given the preference to sorts which I could obtain in considerable numbers in one place 

 and in a particular class of material, so that I could get it sent me by country friends 

 when I was in London, or collect them myself when I was in the country, without the 

 great loss of time involved in hunting for solitary wandering species of these active 

 creatures. For this reason Lcelaps stabularis, Koch, was one of those chosen, because 

 it can be obtained in large numbers in the chaff and fodder in farmhouse stables ; 

 my principal supplies of this Acarid came from Cornwall. For the same reason a 

 species which I be ieve is Holotaspis mouUvagus, Berlese*, was also used because the 

 females of it can be obtained in large numbers in cucumber and other hot-beds and 

 in similar places. Most of my specimens of this species were found and investigated at 

 Ragaz in Switzerland. I, however, did not succeed in finding a single male of this 

 Gamasid, although I was anxious to do so. Another species found with it in the same 

 place, but far less abundantly, was Holotaspis marginatiis, Herm., of which I obtained 

 one male, but one only. In the other species investigated the males were nearly in as 

 great numbers as the females. 



For the same reasons Gamasids which lived in the nests of other animals were very 

 convenient, and indeed were chiefly utilized, not from the variations in organization 

 being in any way connected with parasitism, for the larger number were not parasitic, 

 but only used the nests as a convenient place to live in, or as one that attracted small 



* My species closely resembles Berlese's drawing and description ; but it is impossible to bo certain, because we 

 neither of us found the male, and that is the distinctive sex in GamasinsB. Although he names his species, he suggests 

 that it was a nymph : mine certainly was not immature, as the female constantly contained a fully-developed egg 

 with the embryo formed and almost ready to emerge (PI. XXXV. fig. 71). I have drawn the epistome of my 

 species (PL XXXII. fig. IS), as it perhaps varies a little from Berlese's plate. 



