The Diptera larvae can be divided from an ethnological point of view into four categories: and the members of each, though of diverse systematic affinities, possess in common certain structural characters, which Keilin (1912) considers to be adaptations to the manner of life. The categories are as follows: (i) Saprophagous larvae: those which feed on decayed vegetable matter or the excrement of herbivorous animals; these have a buccal armature similar to that of Calliphora or Lucilia: the ventral surface of the basilar piece is feebly chitinized and has a number of longitudinal ridges projecting into the lumen of the pharynx. (ii) Phytophagous larvae, which feed on living plants, as leafminers, root-miners, etc.: these have the bucco-pharyngeal armature more concentrated, the basilar piece more chitinized, with ridges feebly developed or absent, the mandibles modified as several toothed scrapers. (iii) Parasitic larvae: their buccal armature resembles that of parasitic Tachinidae. (iv) Parasitic larvae—carnivorous larvae: It is now known from the researches of Portchinsky (1910), and later of Keilin himself, that a good number of larvae found in excrement are not really coprophagous, but live on other larvae or other small animals found with them in the excrement. These carnivorous larvae attack their prey, perforating its skin, and sucking its contents. For instance, the larvae of Graphomyia maculata, found in liquefied decomposing vegetable matter, feed on larvae of Eristalis and pupa of Tipulidae, those of Calliophris riparia, found among moss, feed on small oligochaete worms and larvae and pupae of Psychodidae. These carnivorous larvae have certain characters in common. Thus the mandibles are sharp, piercing hooks and the basilar piece of the armature is very long, narrow and strongly chitinized and entirely without the internal longitudinal ridges.” (Scott, 1915.)

The results of the study on the digestion of Gastrophilus larvae may be summarized as follows:

(1) Pepsin-like enzymes are totally absent.

(2) The salivary glands secrete a proteolytic enzyme, which has no effect on the digestion of casein, gelatine and fibrin, but acts on milk alone.

(3) The midgut is capable of secreting amylolytic, proteolytic and lipolytic enzymes.

(4) The body fluid contains a strong reducing substance.

(5) The body fluid, as was shown by Khemnitz (1914), contains an amylolytic enzyme which is also capable of converting glycogen into glucose.

(6) Free glycogen and glucose circulate in the body fluid of the larva during the prepupal and possibly the pupal stage also.

(7) The larva of Gastrophilus does not feed on blood, but lives on the fluid material partly digested by its host in the stomach.

(8) For this reason the horses do not show any symptoms even when there is a heavy infestation.

1. The Protozoa from the hindgut of the wood-feeding roaches Panesthia javanica and P. spadica are described.

2. These Protozoa are to be regarded as commensals.

3. They belong to three subphyla of the phylum Protozoa.

4. Two are flagellates, Monocercomonoides panesthiae sp.nov. and Hexamita cryptocerci Cleveland.

5. Two species of Endamoeba are described, E. philippinensis sp.nov. and E. javanica sp.nov., the former small and a bacteria feeder, the latter large and xylophagous.

6. An unidentified amoeba was observed in one roach.

7. Nyctotherus uichancoi sp.nov. was found in the majority of Panesthia javanica and infrequently in P. spadica.

8. Nine species of heterotrichous ciliates (Clevelandia gen.nov. and Paraclevelandia gen.nov.) make up the family Clevelandiidae fam.nov.

9. This family is characterized by the posterior position of the mouth which may occur at the end of a projection, varying in length. It is closely related to the family Plagiotomidae, to which Nyctotherus belongs.

10. A well-integrated neuromotor system is described in the family Clevelandiidae, being practically identical in all members.

11. The relationships of Panesthia, Cryptocercus, the domestic cockroaches, and the termites are discussed on the basis of their protozoan faunas.

Among the shore crabs the genus Callianassa is quite cosmopolitan; its species are widely distributed and seem also to be peculiarly susceptible to parasitism. Wherever they have been examined carefully they have yielded semi-parasitic copepods, sometimes in considerable numbers. Such forms have been reported from both the east and west coast of North America, from the Mediterranean and from the British Isles. Recently 150 of these semi-parasites were sent to the United States National Museum from Salaverry near Trujillo on the coast of northern Peru. They were taken by Mr Floyd Sears, agent of the Grace Line at Salaverry, from the branchial chamber of a species of Callianassa on the Peruvian coast. They prove to be new species belonging to two genera of cyclopid copepods and are here described and figured.

1. Onchocerca is recorded for the first time from English-bred cattle.

2. A specific diagnosis of O. gutturosa is made, O. bovis being regarded as a synonym. It is suggested that Stiles's description of Filaria lienalis may have referred to this species.

3. The microfilariae occur in the skin of infected cows, and blood-sucking flies of the genus Simulium were found to be the vectors.

4. Complete development was observed in S. ornatum and partial development in S. erythrocephalum. S. ornatum appears to be a very efficient intermediate host, as over 40 per cent became infected.

5. Culicoides nubeculosus, the vector of Onchocerca cervicalis of horses, does not appear to carry the bovine Onchocerca.

Among the new facts discovered in the course of the writer's investigation on the function of the polar filament of the spore of Nosema bombycis (Ohshima, 1927), the following two are considered the most important:

(1) As soon as its filament extrusion is accomplished in the midgut of a silkworm, the spore discharges a viscous fluid through the tube of the filament. This fluid remains hanging in a spherical shape at the extremity of the filament.

(2) Both the polar filament and the viscous fluid are speedily digested by the digestive ferment of the silkworm in a few seconds.

A brief summary of previous work done on the life history and the biology of fleas is given. The duration of various well-defined periods during the course of metamorphosis of the flea at temperature 23° C. and 90 per cent relative humidity is recorded.

It is experimentally proved that blood, although the most important part of the nutritional requirements of the flea larvae, is by itself not sufficient for their normal and successful development. The flea larvae require an additional food which in nature is supplied by the organic refuse present in the bed of the host of the adult fleas.

Experiments were carried out to determine the nutritional value of different constituents of the blood and it was found that the fibrin has no nutritive value to the flea larvae, while the serum and red corpuscles have equal nutritive value. Lagging larvae are the result of some deficiency in the food. The serum possesses all the essential proteins for the normal development of flea larvae but lack of the required amount of iron in it increases the percentage of mortality and delays the development. On the other hand the red corpuscles or haemoglobin, though rich in proteins containing iron but on account of the poverty of some other proteins necessary for the normal development prolong the development and increase the percentage of mortality. It was further experimentally proved that flea larvae require blood for their development in order to obtain the necessary supply of iron for their normal growth. The denatured proteins of the blood and its constituents have no nutritive value for the flea larvae.

The coccidian dealt with in this paper is a parasite of the blood, fat bodies and connective tissue of Tribolium ferrugineum. W. A. Riley and L. Krogh were the first and perhaps the only ones who noticed stages of this parasite, when studying the histology of the larvae of this beetle. They found the pupae and adults uninfected, but in the course of the present work some of them were heavily infected, though only a small number could be examined.

From the foregoing brief descriptions it is clear that the larva of Trichomyia urbica stands apart from other psychodid larvae not only in its mode of life, as a wood-borer, but also in its morphology. The regularly cylindrical body, devoid of dorsal plaques and long setae and the densely chitinized head give it a very different appearance from that of other psychodid larvae.

The small and heavily chitinized antennae are very different from those found in larvae of Phlebotomus, in which they are 3-segmented; Psychodes, in which they are delicate and dome-like; Sycorax, in which they are long and 4-segmented (Feuerborn, 1933); and Maruina, in which they are formed of small rods (Feuerborn, 1933).

The massive toothed mandibles, devoid of sensory processes, differ greatly from those of other genera of psychodids except Phlebotomus. Maruina, Sycorax (see Feuerborn, 1933), and Psychodes all have mandibles with large leaf-like processes and many long plumose or pectinate setae and sensory hairs or processes.

The maxillae, in all the three genera examined above, are delicate plates with ill-defined areas representing the maxillary palps, and with many delicate teeth, long setae and sensory processes arising from the body of the maxilla.

The lower lip in Trichomyia is very simple and the mentum is hardly distinguishable. In this respect it resembles Psychodes where the mentum is a simple transverse plate, and Maruina (see Feuerborn, 1933) in which it is similar except that the anterior border of the plate is fringed with long setae. In Phlebotomus the mentum is a densely chitinized plate with strong teeth on its anterior margin.

The anterior spiracles appear to be much alike in all the genera in which they are present; but in the position of the posterior spiracles Trichomyia, in which they are placed far back on the dorso-lateral region of the last segment, differs from all other genera examined except Phlebotomus, in which they occupy a similar position.

Therefore, as regards the shape of the body, nature of the cuticle, absence of long setae and of dorsal plaques, and the structure of the antennae and labrum, the larva of Trichomyia differs from all other psychodid larvae. It shares with the larva of Phlebotomus the possession of strong, simple, toothed, mandibles devoid of long setae and sensory processes. It also resembles Phlebotomus in the poorly defined epipharynx and premandibles on the labrum, and in the position of the posterior spiracles near the middle of the last segment. The weakly developed mentum of Trichomyia larvae, however, differs greatly from that of Phlebotomus larvae in which the mentum is very strongly developed as a toothed plate.

Previous records and descriptions of the fungus known as Acladium castellanii, a human pathogen in the south-east of Asia and Europe and in Brazil, are cited and an account is given of its morphology when studied in culture on organic media.

It is concluded that it is closely related to, and perhaps merely a strain of, the widely distributed Sporotrichum schencki, the commonest cause of human and equine sporotrichosis, and that the term acladiosis as denominating a distinct disease should be deleted.

An account is given of an investigation of the causes of error in estimating virus concentrations by the local lesion method. The irregularities were found to be due to:

(1) Variations in the response of (a) whole plants; (b) individual leaves.

(2) Variations in the volume of liquid used.

(3) Variations in the probability of the production of local lesions.

(4) Variations in the percentage of leaf hairs broken during the inoculation process.

An apparatus is described, the use of which reduces these irregularities to a minimum.