Preparation of Invertebrates for WJiole Mounts and Sections 375 



pure glycerine, mount in glycerine jelly (page 119). Helminth ova also 

 (an be mounted in this way. For other methods see Whole Mounts, 

 page 379. 



Microfilaria. Blood infected with microfilaria is smeared and dried 

 as for any blood smear. Then fix in any mercuric chloride fixative and 

 stain with Delafield's hematoxylin. If it is preferable to have the slides 

 dehemoglobinized, after fixation treat them Avith 2% formalin plus 1% 

 of acetic acid: 5 minutes. Wash and stain. An alternate method is to 

 smear and dry; dehemoglobinize in 5% acetic acid and air dry; fix in 

 methyl alcohol and stain with Giemsa (page 225). 



BRYOZOA. 



Anesthetize with menthol. Fix salt water forms in chromo-acetic 

 (10% chromic acid, 7-10 ml.; 10%, acetic acid, 10 ml.; water to make 

 100 ml.). Fix fresh-Avater forms in 10% formalin. 



ANNELIDA. 



Earthworms. If sections of worms (aquatic or terrestrial) are desired, 

 the intestines must be freed of grit and other tough particles. 



Several methods have been devised for earthworms. Cocke (1938) 

 feeds them on cornmeal and agar (1:1) and some chopped lettuce for 3 

 days, changing the food every day. Becker and Roudabush (1935) recom- 

 mend a container with the bottom covered with agar. Wash off the agar 

 tuice a day for 3-4 days. Moistened blotting paper can be used. When 

 the animals are free from grit, place them in a flat dish with just enough 

 water to cover them. Slowiy siphon in 50% alcohol until the strength 

 of the solution is about 10% of alcohol. Chloroform also can be used 

 for narcotizing. Fix in Bouin's or mercuric chloride saturated in 80% 

 alcohol plus 5% of acetic acid. The worms may be dipped up and down 

 in the fixative and then supported by wire through a posterior segment, 

 hanging down in the fixative, or placed in short lengths of glass tubing 

 in fixative to keep them straight. This is necessary if perfect sagittal 

 sections are to be cut. Embedding is probably most successful by the 

 butyl alcohol method. After removal of mercuric chloride in iodized 

 80% alcohol, transfer to n or tertiary butyl alcohol: 24 hours (change 

 once). Transfer to butyl alcohol saturated with paraffin (in 56-60°C 

 oven): 24 hours. Pure paraffin: 24 hours and embed. 



Sea worms can be kept in a container of clean sea water, changed 

 every day for 2 or 3 days, then anesthetized with chloroform and fixed, 

 using fast-penetrating fixative (Bouin's, or a mercuric chloride fixative). 



