Dr. Holló Ferenc - Dr. Murai Éva szerk.: Parasitologia Hungarica 5. (Budapest, 1972)

the 9th to the 20th day of incubation/, on eggs exposed to light

. Illumination had an intensity of 50 lux for half an hour in every case. The hatched miracidia were pipetted and killed in 2 per cent formalin and counted under the preparing microscope. Miracidia structures were examined partly in vivo, partly in a fixed state. To reduce their movements, a solution of 3-5 per cent methylcellulose

, 3 per cent urethan, or polyvinyl alcohol /recommended by WILLMOTT, 1952/ were used. Of the vital staining materials, Nile-blue sulphate, methylene-blue and neutralred proved to give the best results. For detecting the epidermal structures, the silver technique described by LYNCH /1933/ was applied. With the aim of examining the terebratorial papillae, preparations were made by ANDERSON'S method /1958/. Miracidia were fixed in BOUIN, GILSON, RABLE or OZAKI mixtures, embedded in paraffin, then the 5-10 /a- thick sections were stained with haematoxyline

. The muscle fibres were detected by the MALLORY method or stained with iron-haematoxyline according to HEIDENHAIN. Observations and results Size and structure of eggs P. daubneyi eggs vary in shape, they may be pyriform, oval, elliptical, flattened elliptic etc. /photos 5-11

,14/. Their opercular end is generally more attenuate, the antiopercular pole bears a minute asymmetrically situated spine /photo 17/

. According to 3280 measurements, the eggs are 102,3-174,2 /u> long and 48,5-94,8 yu^wide. Dimensions between the extreme values are distributed as shown in Table 1.