General Program for Preparation of a Chitinous Specimen with Pressure

In the previous series I stretched a rather simple mounting technique out to a few thousand words. I did my best to make things clear and explain the why and how of things. It’s easy to understand that way, but it’s easier to follow along with brevity. Here’s the same information all in one page and about 500 words. Easy to print out and refer to as required.

1) Remove killed and fixed specimen from storage, clean superficially with a camel hair brush, and bring into distilled water if necessary (removing fixatives such as alcohol or formalin). Dry specimens do not need to be brought into distilled water.
2) Place superficially cleaned specimens into a 10-15% solution of caustic potash (Potassium Hydroxide) or caustic soda (Sodium Hydroxide) for macerating. Ensure sufficient of the macerating solution is present to remain at 10% concentration when the fluid diffused from the specimen(s) are added to it.
3) Retain specimen in solution for 12-72 hours, or until visual signs of internal organ decomposition. Alternatively, heat the specimen in solution for up to 30 minutes to accelerate the process, do not allow the vessel to “boil dry.”
4) Remove specimen from macerating solution and wash in several changes of distilled water.
5) Add 5 or more drops of acetic acid to specimen in distilled water, both to ensure complete removal of macerating solution and to further soften chitinous tissue. If required specimens may be stored in strong acetic acid until ready to continue.
6) Apply pressure to bulbous portions of the specimen with the butt of a camel hair brush or needle holder, working from the head and expressing liquefied internal organs through the anus. For small ants and thin bodied specimens this treatment is not required.
7) Lay specimen out in position desired for mounting on slip not suited for general mounting (slips with chips or imperfections may be used). Arrange all appendages as desired before continuing.
8) Place a second slip over the first applying pressure first at the head of the specimen, hold slips together closely and prevent slipping of one across the other.
9) Use clips or other convenient apparatus to bind slips tightly together.
10) Place bound slips into vessel of anhydrous alcohol (95% denatured if none better is available) and leave for not less than 1 hour to dehydrate and harden. Specimens may be left in alcohol until convenient to proceed.
11) Take bound slips from alcohol and hold close while removing clips holding them. Separate slips flooding with alcohol so that the specimen does not adhere.
12) Wash specimen into watch glass with alcohol and use a camel hair brush to remove any internal debris that adhere to the specimen.
13) Transfer specimen to clearer required by the final mounting medium to be used. Leave for as long as the particular clearer demands. 1-24 hours is the usual time.
14) Take specimen from clearer and allow excess to run off before placing onto clean slip for mounting.
15) Apply mountant to one side of a cleaned cover glass of appropriate size for the specimen and lower directly onto specimen.
16) Add mountant at edge of cover glass if insufficient mountant was used, clean exuded mountant from slide in the event of excess.
17) Affix temporary label to slide and put up for mountant to cure as required.

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3 thoughts on “General Program for Preparation of a Chitinous Specimen with Pressure

  1. Splendid!
    I am currently trying to sort out a mirror on my meopta microscope. I got a mirror for it but the little peg didn’t fit in the hole. I managed to change the peg for a screw and was very pleased with my Heath Robinson mirror. I put a slide under the microscope and spent a good hour wondering why I couldn’t centre the condenser adequately – a new condenser, incidentally. Eventually, I realised that the mirror is sticking out too far. There’s nothing wrong with the condenser at all.

    Lesson 1 in microscopy: don’t test two unknowns at once. One variable at a time! Ha ha!

  2. Thanks for this! I have made a few dozen insect slides so far (ants and spiders mostly), and your program has been a great help. Greetings from the Netherlands.

    • Glad it has helped get you started mounting with pressure. Don’t be afraid to try other subjects, or to modify the process. For the more delicate species it may help to forgo the acetic acid until after the organs have been expelled, I may put up a bit of a revised program some time soon.

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