Copepoda of the Okoboji Region

BRANCH= ARTHROPODA, Class: Crustacea, SUBCLASS: ENTOMOSTRACA, Order: COPEPODA, Suborder: Eucopepoda, Group: GNATHOSTOMA, FAMlLY:CENTROPAGIDAE, Genus Diaptomu

Cladocera of the Okoboji Region

The following list of Cladocera is a continuation of the list published in the Proceedings of the Iowa Academy of Science for 1917. It represents the species collected during the summer of 1919, from June 24 to September 1

A List of Entomostraca from the Okoboji Region

45. A list of entomostracan The following is a list of Entomostraca collected by the writer at the Macbride Lakeside Laboratory during the August session, 1916. The starred forms have been previously reported from this region by Prof. L. S. Ross in volumes III and IV of the Proceedings of the Academy

The Development of the Ovary and Oviduct of the Gold Fish

Sex differentiation in the gold fish begins in embryos of about 14 to 16 mm. in length. In the female the germ cells increase rapidly in size and have a tendency to become arranged in rows. A distinct central nucleolus is not present, but round nucleolar bodies are arranged peripherally against the nuclear membrane. These bodies seem to give off buds which pass through the nuclear membrane into the cytoplasm. During the early stages the cytoplasm becomes basophilic. In very young oocytes this is limited to a narrow zone immediately surrounding the nucleus. It then spreads peripherally until the entire cytoplasm stains deeply with basic stains. When yolk formation begins the cytoplasm changes back to the acidophilic condition again

Temperature Studies of Lake Okoboji for 1925

Continuing the work begun by Tilton (\u2715-\u2716) and Birge and Juday (\u2719), the writer has, since 1922, made daily observations of the water temperatures of Lake Okoboji. Sample readings have been reported from time to time. Temperature curves for the several years under observation show considerable variation in the degree of zonation. Tilton\u27s curves do not show any marked differentiation into epilimnion, thermocline, and hypolimnion. On the other hand in 1919 Birge and Juday\u27s observations show a very distinct zonation. This is even more marked in the curves for 1922 (Stromsten \u2723) and reaches its climax in 1923 (fig. 1). In 1924 the zonation becomes less distinct (fig. 1) while in 1925 no distinct thermocline seems to have developed

The Development of the Posterior Lymph Hearts of the Loggerhead Turtle

Recently, in a paper read before the American Society of Zoologists, central section, the writer presented some observations which indicated that the lymphatic system of turtles has an origin more or less independent of the venous system. Since then later investigations on the Chelonian lymphatics confirm and strengthen this view. Even in the development of the posterior lymph hearts, which are generally conceded to be direct derivatives from early redundant embryonic veins, we find that the process is initiated, at least, by the dilation and confluence of mesenchymal spaces

The Development of Lymph Channels in Turtles by the Fusion of Mesenchymal Spaces

The theory that the lymphatic system is budded off from the venous system is a direct product of a special method of investigation, i.e., the injection method

A New Apparatus for Measuring Deep Water Temperatures

There has always been a certain fascination in the study of things related to great bodies of water. The curiosity to know what is going on beneath the turbulent waves when the storm is raging and what the conditions are beneath the smooth surface when all is quiet has ever challenged our spirit of investigation. What are the environmental conditions of aquatic life has given considerable impetus to the physical and chemical phases of limnology. Temperature seems so closely interwoven into the environmental complex that careful and exact measurement of this factor is one of the first things to be done in any ecological study

The Development of Musk Glands in the Loggerhead Turtle

Musk glands were first described in turtles by Dr. William Peters in 1848, and independently, in the same year, by Rathke. The glands do not appear to be present in all turtles, but when present consist of one or two pairs according to the species of turtle. One pair is located at the anterolateral angles of the carapace, just beneath the peritoneum. The second pair, when present, is found at the posterolateral angles, one on each side. According to Peters, the secretion is a brownish, watery fluid, tasteless, but having a very penetrating odor. The glands are compared to the Kieferdrüsen\u27\u27 of Crocodiles (Mueller\u27s Archives, 1848, 492-6)

Nest-Digging and Egg-Laying Habits of Bell\u27s turtle

During the summer of 1921 some forty or fifty Bell\u27s turtles dug their nests on the side of a small hill just north of the Iowa Lakeside Laboratory. This afforded an excellent opportunity for the study of the nest-digging and egg-laying habits of this species of turtle. When the turtle is digging her nest or depositing her eggs she is not easily frightened so that it is possible to get very close to the animal and to use a flash light within an inch or two of the body. On several occasions a number of students at the Laboratory were able to watch the entire process from the time the turtle landed on the shore until it returned to the water again. This paper presents more or less in detail the events that took place in the little more than two hours occupied by the turtle in digging the nest, laying the eggs, and concealing the nest