Gastrothylax crumenifer haemoglobin was isolated, purified, chromatographed, and its molecular weight determined on a calibrated Sephadex G–100 column as well as by sodium dodecyl sulphate by the former and 16 500 by the latter method. The oxygen affinity of the pigment (P50O2) was found to be 6·1 mm Hg at pH 7·4.

The oxidative metabolism of Gastrothylax crumenifer mitochondrial fractions was assayed polarographically at 30°C in the presence of various substrates. Succinate was most readily oxidized, malate and pyruvate were oxidized at subsantially lower retes. The spcific inhibitors such as malonate, KCN, NaN3, oxaloacetate, salicylhydroxamic acid and oligomycin effectively affected the mitochondrial oxygen consumption. The results indicate the presence of oxidative phosphorylation and cytochrome systems. Mitochondrial ATPase was found to be active.

The protein content of fresh homogenates and their corresponding TCA precipitated fractions of 10 different species of helminths was estimated by the methods of Lowry et al. and Spector using the Folin phenol reagent and Coomassie brilliant blue G-250 respectively. The former method gives exaggerated values as compared to the latter method. The parasite phenols, phenolic proteins and catecholamines could be responsible for interference in the Lowry's procedure. The TCA non-precipitable moieties also give colour only with the Folin phenol assay. The pronounced intra-specific differences in the total protein content of helminths reflect their metabolic variations and adaptations. Habitat does not appear to influence the protein content of parasites, however, the effect of host variation was evident in the pouched amphistome G. crumenifer. It is concluded that the dye binding method gives more consistent results and it can be conveniently applied to crude tissue homogenates of helminths.

A comparative studs of the spectral, electrophoretic and isoelectric properties of the haemoglobins of three trematodes. Paramphistomum epiclitum. Gigantocotyle explanatum and Gastrothylax erumenifer was carried out. A high absorption in the beta band region indicates that trematode haemoglobins have high oxygen affinities. Electrophoretic mobilities of all trematode and their host haemoglobins were different. The isoelectric points of trematode haemoglobins were found to focus in the acidic range except that of G. crumenifer haemoglobin I. which focused at an alkaline pH.