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Reduction of aqueous RhCl3 with NaBH4 in the presence of poly(vinyl pyrrolidone) (PVP) yields dense spherical nanostructures. The spherical aggregates, which generally have diameters between 10 and 100 nm, are built from smaller 1−3 nm Rh particles. The dense nanostructures are thermally stable beyond 100 °C, and they have a tendency to form ordered superstructures upon drying. Combining sodium n-dodecyl sulfate (SDS) with PVP modifies the size and morphology of the primary 1−3 nm particles, but does not change the spherical shape of the aggregates except at high concentrations of SDS. Small-angle X-ray scattering measurements show that the large aggregates are formed directly in solution from small Rh particles, consistent with TEM and AFM results. Magnetic measurements indicate that the Rh nanoparticle aggregates are Pauli paramagnetic.

A simple, fast, and robust approach to colloidal assembly on patterned surfaces was developed. The approach involves the rapid settling and dewetting of suspensions of spherical colloids on lithographically templated surfaces. Using this method, we can quickly and easily fabricate close-packed colloidal crystal microarrays of both silica and polystyrene spheres that range in size from 500 nm to 4.5 μm. The microarrays tend to induce the formation of monolayer colloidal crystals, which can be interconnected and removed from the templates as free-standing colloidal crystal slabs. The same approach can also be used to assemble two-dimensional colloidal crystal superlattices that can adopt a variety of structures. Graphite, kagome, body-centered cubic, open hexagonal, tetragonal, and linear chain structures can all be quickly accessed by adjusting the ratio of the sphere diameter to the template diameter.

The life cycle of Philophthalmus megalurus includes a minimum of five polymorphic generations: the hermaphroditic adult in the conjunctival sacs of birds, a paedogenetic miracidium which develops in the egg, and the sporocyst, mother redia, and daughter redia which parasitize the snail host. Daughter rediae produce a few granddaughter rediae first and then cercariae. The diploid chromosome number is 20 and gametogenesis in the adult is typical with 10 bivalents appearing during the first maturation division of gametocytes. In all generations, an unequal first cleavage produces a smaller propagatory, and a larger somatic cell. Unequal division of the propagatory cell again results in a larger somatic and a smaller daughter propagatory cell from which the sporocyst develops within the miracidium before the egg hatches. In other generations, repeated unequal division of the daughter propagatory cell results in small, dark germinal cells which may multiply by mitosis. They are interpreted as oögonia which transform directly to oöcytes in all generations except cercarial embryos. In that process, each undergoes meiotic prophase to diakinesis with the appearance of 10 bivalent chromosomes, then returns to interphase, grows, and becomes the large “germinal cell” typical of sporocysts and rediae of trematodes. Each oöcyte cleaves without polar body formation to form an embryo of the next generation. Reproduction in the germinal sacs accordingly is diploid parthenogenesis and polyembryony is not involved. The term “larval trematodes” for generations reproducing in the molluscan host is inaccurate and should be restricted to miracidia and cercariae, the only stages that undergo metamorphosis.

The fine structure of photoreceptors is described in miracidia of Fasciola hepatica, Heronimus chelydrae, Allocreadium lobatum, and Spirorchis sp., and in a spirorchiid cercaria. All have in common eyespots consisting of pigment cells with chambers occupied by rhabdomeres consisting of retinular cell dendrites with numerous microvilli. Photoreceptors of the miracidia show a bilateral asymmetry which is most pronounced in H. chelydrae with a pair of well separated eyespots unequal in size. The smaller right one consists of a pigment cell and two rhabdomeres; the larger left eyespot has an anterior pigment cell with two rhabdomeres and a posterior cell containing one rhabdomere. Photoreceptors in the other species of miracidia also have five rhabdomeres but contain only two pigment cells which are closely apposed. Each contains a pair of lateral rhabdomeres and a fifth one occupies a posteromedian extension of the left pigment cell. In the number of rhabdomeres, their relationship to pigment cells and the resulting asymmetry, photoreceptors are more alike in the distantly related species of miracidia studied than they are in ocellate cercariae or even in the miracidium and cercaria of the same species or two closely related ones. From the asymmetry of photoreceptors in larvae of certain flatworms other than digenetic trematodes, it seems that eyespots of miracidia have retained an ancestral pattern whereas the diversity of photoreceptors in cercariae reflects the varied phototactic behavior of those larvae which complete their life cycles by all the means known for cercariae with a free-swimming period. In both miracidia and cercariae, photoreceptors show an anterior-posterior organization that would seem to be concerned with orientation of the larvae with respect to light.

The life history of Spelotrema nicolliCable and Hunninen, 1938, has been traced experimentally and the various stages have been described. The cercaria develops in sporocysts in the digestive gland of Bittium alternatum(Say). The blue crab, Callinectes sapidusRathbun, serves as the second intermediate host. In experimental infections, the cercariae were found to penetrate the gills, and pass by way of the blood stream to the tissues. Metacercariae from naturally infected crabs were fed to young herring gulls, Larus argentatusPontoppidan, from all of which numerous adult S. nicolliwere recovered.A re-description of Cercaria nassicolaCable and Hunninen, 1938, is given. This ubiquitous species occurs in the mud snail, Nassa obsoleta(Say).The taxonomy and relationships of the Microphallidae are discussed.

The life history of Anisoporus manteriHunninen and Cable, 1940, has been traced experimentally. The cercaria, a cotylomicrocercous type, develops in sporocysts in the marine snail, Mitrella lunata(Say) and encysts in the marine amphipods, Carinogammarus mucronatus(Say) and Amphithoe¨ longimanaSmith. Old metacercariae contain eggs in the uterus and cystic fluid. Adult worms occur in the intestine of the marine fishes, Syngnathus fuscusStorer, Paralichthys dentatus(Linnaeus), Hippoglossoides platessoides(Fabricius), Apeltes quadracus(Mitchill), Fundulus heteroclitus(Linnaeus) and F. majalis(Walbaum).It is proposed that the family Allocreadiidae be restricted to include only trematodes having cotylomicrocercous cercariae and simplified excretory patterns, since the type genus, Allocreadium, would be included in the restricted family. Consequently, the family name, Opecoelidae, would be suppressed as a synonym of Allocreadiidae sensu stricto.

The life history of Deropristis inflatahas been demonstrated experimentally. The cercaria is a trichocercous form developing in simple rediae in the marine snail, Bittium alternatum.It enc?ysts in Nereis virensand the eel, Anguilla rostrataserves as the natural definitive host which becomes infected by eating annelids containing metacercariae.The genus Deropristisand Dihemistephanus sturionisare excluded from the family Acanthocolpidae which is redefined to include for the first time the genera Lepidauchen, Pleorchis, and Pseudolepidapedon.The family Pleorchiidae thereby becomes invalid.It is proposed that the family Allocreadiidae be restricted to include only forms known or believed likely to have ophthalmoxiphidiocercariae with main excretory tubules not reaching the cephalic region of the body before receiving secondary tubules. The Allocreadiidae and Acanthocolpidae are regarded as separate but closely related families.The genus Anallocreadiumis reduced to synonymy with Homalometronand the subfamily Anallocreadiinae is renamed Homalometrinae. The Lepocreadiinae, Homalometrinae, and new subfamily Deropristiinae are regarded as a distinct family, the Lepocreadiidae. The family Gyliauchenidae is believed to be nearer the Lepocrediidae than the Paramphistomoidea. Whether the Allocreadiidae, Acanthocolpidae, Opecoelidae, Lepocreadiidae and Gyliauchenidae constitute only one or more than one superfamily is not apparent from the fragmentary knowledge of life histories and embryology.

Cercaria laevicardiisp. nov. is described from the marine lamellibranch, Laevicardium mortoni. The cercaria develops in simple sporocysts and is similar to the larva of Bacciger bacciger. The excretory formula is 2 [(3 + 3) + (3 + 3)] and the structure and development of the excretory system is such that the larva is interpreted as having been derived from the furcocercous type. Various caudal modifications in fellodistomatid cercariae are discussed and the possible phylogenetic significance of some types is mentioned.

A letter to the editor is presented regarding professor Ajax Carlson.