356 CHAPTER XXVI. 



643. Trematoda. COE (Zool. Jahrb., Abth. Morph., ix, 1896, 

 pp. 563, 566) fixes the Miracidia of Distomum for general 

 purposes with the usual fixatives ; but for the special study 

 of the excretory system he kills them with osmic acid, rinses 

 with distilled water, and puts them for a couple of days into 

 per cent, solution of silver nitrate. 



644. Nematoda. BOVERI (Jena. Zeit., xxi, 1887, p. 423) 

 fixes the ova of Ascaris in his picro-acetic acid (after which 

 treatment I should say you may easily see anything you like 

 to imagine in them). 



ZUR STEASSEN (Arch. Entwickelungsmecli., iii, 1896, p. 29) 

 fixes them for twenty- four hours in a mixture of 4 parts 

 96 per cent, alcohol and 1 part acetic acid (much too long, 

 I should say), brings them into pure alcohol, stains with 

 hydrochloric acid carmine, and brings them gradually into 

 glycerin. 



Similarly ZOJA (Arch. f. m%k. Anat., xlvii, 1896, p. 218) 

 and ERLANGER (ibid., xlix, 1897, p. 309). Zoja stained with 

 Bismarck brown and examined in dilute glycerin ; Erlanger 

 made paraffin sections and stained with iron hsematoxylin. 



KOSTANECKI and SIEDLECKI (ibid., xlviii, 1896, p. 184) 

 employed concentrated sublimate solution, or 3 per cent, 

 nitric acid, or mixtures of these two, for ovarian ova. 



I fancy the best fixative for ova furnished with their cap- 

 sules will be found to be that of G-ILSON CARNOY-LEBRUN 

 ( 84) ; see CARNOY & LEBRON, La Cellule, xiii, 1897, p. 68. 

 After fixation the ova are carefully brought into 80 per cent, 

 alcohol, in which they are preserved. Imbedding should be 

 carefully done, as recommended for the ova of Amphibia 

 ( 600), but they ought not to remain in the pure paraffin 

 for more than a minute to a minute and a half. But these 

 authors prefer the celloidin method. At least six weeks' 

 soaking in the different strengths of celloidin will be neces- 

 sary to ensure penetration. They stain with iron haema- 

 toxylin. 



Echinodermata, Coelenterata, and Porifera. 



See the paragraphs treating of these groups in the chapter 

 on "Zoological Methods." 



