J14 Cytologie und Befruchtung. 



King, Cyrus Ambrose, Observations on the Cytology of 

 Ariospora pulchra Thaxter. (Proc. of the Boston Soc. of 

 Nat. History. Vol. XXXI. 1903. p. 211—245. PI. 11 — 15.) 



Ariospora is a rare and rather inconspicuous fungus, placed by 

 some authors in the Saprolegniaceae and by others in the Peronospora- 

 ceae. Although the plant has constrictions at one or more places in its 

 hyphae, it remains unicellular, except where reproductive organs are cut 

 off. In the formation of zoospores cleavage takes place almost simul- 

 taneously around the surface of each zoospore by the Separation of con- 

 necting meshes, thus differing from the method of progressive cleavage 

 by vacuolar membranes. The zoospores germinate within a few hours 

 after reaching maturity. 



The oogonia contain from thirty-five to fifty-five nuclei. As these 

 nuclei migrate to the periphery, numerous fine meshed patches of cyto- 

 plasm appear and migrate toward the center, where they fuse into one 

 mass bearing some resemblance to a coenocentrum. After the entrance 

 of the sperm, the central mass spreads out into the peripheral cyto- 

 plasm. The oosphere, when mature, is uninucleate; a Single sperm 

 nucleus with some cytoplasm is introduced through the receptive papilla, 

 which is homologous with the receptive papilla in Vaucheria and Oedo- 

 gonium. There is no antheridial tube. As the sexual nuclei approach 

 each other, both put out beaks on their anterior surfaces but later they 

 become spherical. They are always found close together, even in the 

 oldest oospores. As the ooplasm and periplasm become separated, the 

 latter is divided anticlinally into a great number of cells. 



The writer believes that Ariospora belongs with the Peronosporineae 

 but should be placed between Pythium and the Saprolegniaceae. 



Charles J. Chamberlain (Chicago). 



LONGO, B., Ricerche sulle Cucurbltaceae ed il significato 

 del percorso intercellulare (endotropico) del 

 tubetto pollinico (presentata nel Decembre 1902. 

 (Atti dei Lincei Mem. Cl. Sc. fis. mat. e nat. Ser. V. Vol. IV. 

 p. 523—547. Tav. I— VI. Roma 1903.*) 



L'A. s'occupe avant tout de l'origine de l'epais tissu con- 

 ducteur dans l'ovaire des Cucurbita. II rappelle ensuite que 

 les auteurs qui se sont occupes de Cucurbltacees decrivent 

 l'ovaire des Cucurbita comme uni ou triloculaire et il demontre 

 que cela n'est pas exact, parceque chaque ovule des Cucurbita 

 est renferme dans une petite cavite (loggetta) creusee dans les 

 tissus de la pulpe ovarienne. Cette structure est tout-ä-fait 

 particuliere aux Cucurbita, car eile manque dans les autres 

 Cucurbitace'es ; eile est un excellent caractere differentiel pour 

 ce genre. 



L'ovule des especes de Cucurbita examinees par l'A. est 

 pourvu d'un tissu conducteur special, dont la position et le developpe- 

 ment changent dans les differentes especes, comme le demontrent 

 les descriptions que l'A. nous donne des ovules de Cucurbita 

 Pepo L., C. maxima Duch et varietes horticoles, C. Melopepo L., 

 C. ficifolia Bouch., C. foetidissima H. B. K., descriptions illustrees 

 par des dessins schematiques. 



") Memoire couronnee par la „R. Accademia dei Lincei". 



