8 American Midland Naturalist Monograph No. 1 



Preserving fluid. — It is a distinct advantage to use as a preserving fluid 

 one that will dry quickly, thus making the surface characters visible with as 

 little delay as possible. Fluids containing glycerine have the disadvantage or' 

 leaving a "moist" or "tacky" surface which obscures the details of the surface 

 parts. However, glycerine can be removed by washing with 70 percent alcohol. 

 This takes time and subjects the specimen to some danger of injury. Carbon 

 tetrachloride preserves the true colors in ornate ticks to a remarkable decree 

 but makes the specimens very hard and brittle. At the Rocky Mountain Labor- 

 atory 70 percent alcohol is used. This evaporates rapidly and we have not 

 detected that specimens so preserved are more brittle than those placed in 

 fluids containing glycerine. 



When ticks are kept out of the alcohol for some time and also subjected 

 to the heat of a light, it is very desirable to put a drop of alcohol on the 

 specimen occasionally. 



Cleaning. — Cleaning should be avoided if possible, but is sometimes neces- 

 sary, since argasid ticks are often encrusted with coxal fluid which serves as 

 a mild glue. For cleaning it is useful to have at hand a series of small, artist's 

 red sable brushes, the tips of which have been cut off at different lengths, thus 

 affording various degrees of severity for "scrubbing." The cleaning is done 

 under low magnification with the tick immersed in 70 percent alcohol. Care 

 must be taken not to break parts or remove hairs. 



In examining the hypostome in situ it is frequently desirable to remove 

 matter from the mouth parts with a soft brush from which the tip has not 

 been removed. 



When especially clean specimens are needed, as for photographing, it is 

 preferable to use ticks that have recently molted in a clean container. 



Posing. — The specimens are removed from 70 percent alcohol, pressed 

 lightly on soft, absorbent paper (such as is used as a substitute for handker- 

 chiefs) and are then transferred on a microscopical slide to the field of the 

 microscope for examination dorsally and ventrally. When special positions are 

 wanted other aids are used. When working with Dr. Nuttall in England, the 

 senior author saw him using small lumps of modeling clay or "plasticine" 

 which could be stuck to a glass slide and shaped to fit the need — a point, a 

 ridge, a sloping surface, or a groove. Without some such refinement of tech- 

 nique there is danger of failing to make some characters visible. It is common 

 practice in museums and laboratories to hold the tick under the microscope 

 between the points of forceps. This has resulted in injuring valuable specimens. 

 Because of this practice some types which we have seen have lost part or all 

 of the appendages. Parts broken off by manipulation should be put in "micro 

 vials," labelled, and dropped into the larger museum vial along with the dis- 

 membered specimen. 



Dissection. — We have found that it is not always sufficient to study the 

 hypostome and some other parts in situ. Even with good vision and a satis- 

 factory microscope it is frequently impossible to see the essential characters 

 clearly. Dissection and mounting of parts then become necessary. 



