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Sexual mode in colonial animals is expressed at the zooid, colony, and genet level; all three must be characterized to understand sexuality in these animals. I carried out such an examination of the sexual mode of a colonial kamptozoan (entoproct), Barentsia hildegardae, at Friday Harbor, Washington. Calyces never contained both ovaries and testes, and colonies never contained both male and female calyces. Calyces and colonies (including replicate colonies from the same genet) monitored over two years did not change sex. These results suggest that B. hildegardae is comprehensively gonochoric. For comparison, I examined the sexual mode of five other species in the genus Barentsia. Barentsia benedeni, B. conferta, and B. ramosa also appear to be comprehensively gonochoric. Barentsia discreta is hermaphroditic at the colony level, with gonochoric calyces whose sex is environmentally determined, as noted by previous workers. Barentsia aggregata has simultaneously hermaphroditic calyces; this was reported by the authors who described it, but has escaped notice in subsequent reviews of kamptozoan biology. There are thus three contrasting modes of sex within the genus Barentsia. All three modes also occur in colonial cnidarians, and two of them are known in bryozoans, colonial hemichordates, and colonial urochordates. These disparate sexual modes may have evolved as adaptations to differing environmental conditions or population densities.

The highly variable Ipomopsis aggregata complex (Polemoniaceae) is revised on the basis of extensive field and herbarium study. A three-species system consisting of I. aggregata, I. arizonica, and I. tenuituba is adopted. Seven geographical subspecies are recognized in I. aggregata, namely, subspecies formosissima, aggregata, bridgesii, collina, attenuata. weberi subsp. nov., and candida. In their geographical and breeding relationships the first five subspecies are geographical races, and the last two are semispecies. Geographical variations are described but not recognized taxonomically in I. arizonica and I. tenuituba. Local racial variation is common in the group, and examples are listed for most taxa. Hybridization occurs locally between I. aggregata and I. tenuituba.

Ipomopsis aggregata and I. tenuituba are sympatric over a wide area in the mountains of western North America. Ipomopsis tenuituba is subalpine and sphingophilous, while the subspecies of I. aggregata that are sympatric with it occur at lower elevations and are ornithophilous. The ecological and floral isolation breaks down locally, and hybridization ensues. A hybrid swarm is reported in northern Arizona. Introgression takes place, and we describe introgressive populations of I. aggregata from several sites in Colorado and Utah and introgressive populations of I. tenuituba from Colorado and California. Individual variation associated with an intermediate character state is a feature of all these populations; indeed, the variability for which the group is noted is largely explained by hybridization. Individual plants in an introgressive population of I. tenuituba in California show gametophyte segregation for pollen color differences between the parental species. Differences between two widespread altitudi...

1. Embryonic and adult Cymatogaster aggregata have been subjected to scale homotransplantations.2. Homografts are rejected after a short period of time. The time required for graft rejection is temperature-dependent.3. Increased sensitivity to homografts results from successive transplantations.4. Intra-ovarian embryos used in these experiments were not capable of rejecting scale homografts.5. Immature free-living fish rejected homografts, but more slowly than adults.6. Pregnant females can transfer homograft sensitivity to intra-ovarian embryos. It is hypothesized that circulating antibody is passed to the embryo via the ovarian fluid and the embryonic hindgut.

1. The osmoregulatory abilities of adult and embryonic Cymatogaster aggregata were tested by determining serum freezing points and weight changes after exposure to dilutions of sea water ranging between 15 and 100 per cent.2. Adults were able to regulate in external media ranging between 20 and 100 per cent sea water. The greatest deviations of weight and serum freezing point from the normal occur after one to two days in the experimental media. Regulation in all media is complete at or before nine days of exposure.3. The ability of embryos to regulate is proportional to their stage of development. The youngest animals tested regulate only in media with values between 25 and 36 per cent sea water.4. Similar though less extensive experiments were performed with adult Amphistichus argenteus and Micrometrus minimus. The osmoregulatory ability of these species is identical to that of adult C. aggregata.5. Preliminary experiments using Cl36 as a tracer indicate that the branchial salt secretory mechanism prese...

1. Normal human sera were found to agglutinate the erythrocytes of the shiner sea-perch (Cymatogaster aggregata) and of the kingfish (Genyonemus lineatus).2. Agglutination was shown to occur by virtue of four different antigens, each species having two of these four in its erythrocytes.3. Of these, Genyonemus had an antigen with a specificity closely resembling the human B substance (designated here as F-1) and a species-specific antigen (F-2) peculiar to itself.4. Cymatogaster had a species-specific antigen (F-3) and an antigen with a specificity resembling that of the Forssman antigen (F-4).5. No individual variations were found in either fish with respect to these antigens.