The eggs of 30 female chinook salmon, Oncorhynchus tshawytscha (Walbaum), were collected at spawning. Some eggs from each fish were collected for bacteriologic study. Two salmon produced eggs judged to be of poor quality which were not used. The remaining 28 of the 30 groups of eggs were fertilized from a single sperm pool and the eggs incubated in separate groups. Mortality data on the developing salmon were recorded regularly through the twelfth week on feed. Unfertihzed eggs from each group were surface-disinfected with an iodine solution, then crushed and subjected to a culture procedure designed to permit growth of as many bacterial types as possible. Bacteria were cultured and identified, and a comparison made of the types of organisms present in eggs from groups which later incurred high or low mortalities. Bacteria were recovered from both groups of salmon eggs. Although no single organism could be identified as a cause of increased mortality, the more frequent occurrence in the eggs of the 'high mortality' group of species of Vibrio, Listeria, Corynebacterium and Staphylococcus suggests that these bacteria may play a role. It is suggested that the cause of so-called early Ufestage disease of salmon is muUifactorial.

Recent investigators suggest that dermatomes extend as consecutive bands from the dorsal median line and question the existence of dorsal axial lines. Our observations were made on serial sections of human embryos and fetuses prepared with neurofibrillar stains.Cervical nerves 1, 6, 7 and 8 failed to have cutaneous branches in most cases, the remainder usually had cutaneous branches.With a few exceptions in T 1, all thoracic dorsal rami had cutaneous branches. Usually T 1, 2 and 3 became cutaneous through medial branches, while T 9 through 12 did so through lateral branches. However T 4 through 8 constitute a transition zone where many of these nerves became cutaneous through both medial and lateral branches. Thoracic 4, 5 and 6 tended to have cutaneous distribution through medial branches, but T 7 and 8 through lateral branches.All lumbar dorsal rami having cutaneous distribution did so through lateral branches, but independent branches became progressively less frequent below L 1.Lumbar 4 lacked direct cutaneous branches in most cases and succeeding nerves in all cases. These nerves form the dorsal sacral plexus. The deficit in cutaneous distribution of lower lumbar rami was not as pronounced as in the lower cervical region. A deficit is significant in relation to dorsal axial lines.

No abstract

Embryos from superovulated female mice that developed in vitro from the two-cell stage were compared with in vivo embryos with respect to yield of blastocytes, number and types of cells, morphology in histologic section, and DNA polymerase activities. Significantly more embryos developed into blastocytes in vitro (93%) than in vivo (18%). Inner cell mass (ICM) cells comprised approximately 30% of total cells in late morula/early blastocyst stage embryos developed either in vitro or in vivo. However, the in vitro embryos developed approximately half the number of total cells as in vivo embryos, did not develop endoderm, and did not develop abembryonic trophoblast cells with morphologic characteristics of late preimplantation in vivo embryos. DNA-dependent DNA polymerase activities in in vitro embryos decreased in correspondence with the decrease in cell number resulting in per cell levels comparable to in vivo embryos. In contrast, the poly (A).oligo(dT)-dependent DNA polymerase activity was the same in embryos developing either in vitro or in vivo, indicating different regulatory mechanisms for the two enzyme activities. A variety of nutrients and growth factors in the culture medium did not increase cell numbers or DNA polymerase activities in embryos cultured for 3 days; extending the culture an additional 24 hours resulted in a loss of ICM cells and decreases in both DNA polymerase activities. These results show that the retarded growth of embryos in vitro is equally distributed between ICM and trophoblast, is not reversed by culture conditions that include serum growth factors, and is not due to decreased cellular levels of DNA polymerase activities.

This is one of a series of papers on the structure and development of the cranial and spinal nerves. These observations were made on serial sections of human embryos and fetuses cut in different planes and stained with various neurological methods. These include the protargol method of Bodian ('36) and the silver gelatin method of Pearson and O'Neill ('46 In accordance with the Nomina Anatomica as revised by the Seventh International Congress of Anatomists of 1963, the terms nervus accessorius (accessory nerve) and musculus sternocleidomastoideus ( sternocleidomastoid muscle) will be used. OBSERVATIONSThis study is primarily concerned with the course of the accessory nerve and its relation to the upper cervical nerves. Since the hypoglossal nerve in mammals represents phylogenetically a fusion of several of the most rostra1 spinal nerves in lower forms, a consideration of this nerve will also be included.A small, spindle shaped ganglion ( fig. 1 ) was found in relation to the hypoglossal nerve on each side of a 47 mm human fetus (no. 101). The peripheral root of each ganglion joined the caudal roots of the hypoglossal nerve on each side and the conjoined bundles passed through the hypoglossal canal. This ganglion lies ventral to the trunk of the spinal accessory nerve and is located just dorsal to the hypoglossal canal. It more closely resembles a dorsal root ganglion of a typical spinal nerve than it does the accessory ganglia along the trunk of the accessory nerve. This is the only human embryo in our collection and in those which we studied at the Carnegie Institution which possessed a ganglion of this type connected to the hypoglossal nerve.The first cervical nerves were studied on both sides in 25 human embryos and fetuses making a total of 50 first cervical nerves. The presence or absence of dorsal root ganglia were noted. When a ganglion was present it was recorded as being small, medium sized or large. These ganglia ranged in size from a small cluster of cells to a mass approximating the size of the dorsal root ganglia of the second cervical nerve. The former were classified as small while the latter were considered to be large. When the ganglia appeared to be about one-half to one-third of the size of the second cervical dorsal root ganglia they were classified as medium sized. Clusters of ganglion cells on some first cervical nerves were often so small that in the gross adult specimen they would probably not be seen without a microscopic examination. The ganglion cells frequently occurred in more than one group or cluster along the course of a dorsal root ( fig. 2 ) . Those located within the spinal dura mater or the