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Normal oogenesis in the adult wasp, Habrobracon juglandis, is described. Accounts are given of: (1) the mitotic behavior of oogonia and cystocytes: (2) the production of synaptonemal complexes by pro-oocytes in the germarium; (3) the formation of an egg chamber and its movement through the vitellarium; (4) the ultrastructural details of the transfer of cytoplasmic organelles to the oocyte by the nurse cells; and (5) the production of accessory muclei and protein yolk spheres in the ooplasm. Comparisons are drawn between Habrobracon and other insects with respect to: (1) the cystocyte divisions, the origin of ring canals, and the control of pro-oocyte differentiation; (2) the possible symbiotic relationships of bacteria which reside in ovarian tissue; (3) the proposed functions performed by accessory nuclei and protein yolk spheres; and (4) the synthesis of rRNA by the nurse cells.

The heat of combustion of aluminum carbide (A1 4 C 3 ) in oxygen was measured by means of bomb calorimetry. The solid product of the combustion consisted of alpha aluminum oxide and another crystalline form of alumina, which was characterized as delta alumina. The heats of combustion were corrected for the formation of the delta aluminum oxide. The results, when combined with the heats of formation of alpha aluminum oxide and carbon dioxide, yielded -49.7 kcal mole -1 for the standard heat of formation of aluminum carbide at 298.15°K with an estimated overall uncertainty of ±1.2 kcal mole -1 .

The heats of the following reactions were measured directly in an electrically calibrated flame calorimeter operated at one atm pressure and 303 °K. OF 2 ( g ) + 2 H 2 ( g ) + 99 H 2 O ( l ) → 2 [ HF ⋅ 50 H 2 O ] ( l ) F 2 ( g ) + H 2 ( g ) + 100 H 2 O ( 1 ) → 2 [ HF ⋅ 50 H 2 O ] ( l ) 1 2    O 2 ( g ) + H 2 ( g ) → H 2 O ( l ) The reactants and products were analyzed for each of the reactions. From these heats we calculated the corresponding heats of formation, as follows: OF 2 ( g )   Δ H f 298.15 ° = + 24.52 ± 1.59  kJ  mol - 1 ( + 5.86 ± 0.38  kcal  mol - 1 ) HF ⋅ 50 H 2 O ( l )   Δ H f 298.15 ° = - 320.83 ± 0.38  kJ  mol - 1 ( - 76.68 ± 0.09  kcal  mol - 1 ) H 2 O ( l )   Δ H f 298.15 ° = - 285.85 ± 0.33  kJ  mol - 1 ( - 68.32 ± 0.08  kcal  mol - 1 ) The uncertainties indicated are the estimates of the overall experimental errors. The value of the average O - F bond energy in OF 2 was calculated to be 191.29 kJ mol -1 (45.72 kcal mol -1 ).

The canals connecting the ovarian cystocytes of Habrobracon juglandis are enclosed by a ring made up of eight leaves. Each leaf is composed of a monolayer of between and 70 short parallel microtubules which may be derived from the mid-body. The sliding of certain leaves past one another allows the ring to dilate as the cystocyte grows.