530 Transactions of the Society. 



XXIX. — Observations on Notommata Wernechii, and its Para- 

 sitism in the Tubes of Vaucheria. By Professor Balbiani.* 

 (.See 'Proceedings,' 11th June, 1879.) 

 Plate XVIII. 

 I. — Historical Summary. 



In the preliminary part of his ' Histoire des Conferves d'Eau Douce,' 

 after describing the horn-hke or tubercular excrescences which 

 originate on the side of the filaments of the Ectosperms (FaWien'a), 

 and constitute the male and female reproductive organs of these 

 unicellular algae, Yaucher adds, that " we must not confound these 

 horns or swellings with another kind of corpuscle frequently met 

 with on the Ectosperm, whose function was long unknown. It 

 differs from the oogonia properly so called, in being larger and of 

 varied form, though always enclosing a rounded black spot, which 

 sometimes seemed to me double. Continuing to observe this black 

 spot, I recognized it as the insect called by Miiller Cyclops lupula. 

 Apparently it lays its eggs on the tube of the Conferva, and causes 

 a similar development to that called pall in plants." t In the 



EXPLANATION OF PLATE XVIII. 



Parts of the Animal, 

 bo, mouth, c c, ciliated cavity, ch, external chorion, ch', internal chorion, 

 c ?J, nervous centre, f, stomach, gr c, caudal glands. <; (7, gastric glands. ^ r, fatty 

 globules arising from the destruction of the gastric glands, g s, salivary glands. 

 in, intestine. /, superior lip of the buccal vestibule. /', lateral lips, m s, stomachal 

 mass. 0, summer eggs. 0', their empty shells. 0", winter eggs, od, oviduct. 

 ce, eye. r, rotatory organ, as, oesophagus. 5, segmental organs, or, ovary. 

 ph, pharynx, t, external integument with the subjacent cellular layer, vb, 

 buccal vestibule, v c, contractile vesicle, v g, germinal vesicle. 



Parts of the Plant. 



h, branch bearing the organs of reproduction, h a, adventitious branches at 

 the summit of the gall, h a', adventitious branches of the base, ca, antheridian 

 cell empty and open, fc, false septum, g, galls formed by the parasite, o, organs 

 of sexual reproduction, r a, antheridian branch, r s, sporaugiferous branch. 

 sp, sporange. -x-, x", points where openings of the parasitic pockets occur. 



Fig. 1. — Tubes of Vaucheria terrestris, with a low power. They show at 00 the 

 reproductive organs, and &t g g the capsules or galls inhabited by Notommata 

 Vferneckii, whose presence is indicated by the internal black jjoint. 



Fig. 2. — Notommata Werneckii (adult) — dorsal face. 



Figs. 3, 4, and 5.— Cephalic extremity, in profile. These figures are intended 

 to show some of the variations of form due to the contractions of this part. 



Figs. 6 and 7. — Same extremity — ventral face. In Fig. 6 the buccal vesti- 

 bule is represented widely open, in Fig. 7 it is half closed. 



Fig. 8. — Posterior extremity. A summer egg is in the oviduct od. 



Fig. 9. — Full-grown Notommata, its body distended by eggs nearly mature. In 



* Translated and abridged from ' Aunales des Sciences Naturelles (Zoologie), 

 vol. vii. (1878)No. ]. 



t ' Histoire des Confer vee d'Eau Douce,' 1803, p. 18. 



