532 Transactions of the Society. 



V. dichotoma and V. racemosa, which, however, only contained eggs 

 which died before hatching. He succeeded, however, in extracting 

 the embryo by breaking the shell, and observed among other 

 characters, the eye, and the jaws with a single tooth. 



Notwithstanding the interest of Ehrenberg's discovery, we find 

 but few observations recorded during the succeeding forty years. 

 In 1839, Morren found club-shaped excrescences on Vaucheria 

 clavata, and within them the parasite and its eggs. Opening 

 one of the cysts, Morren saw the animalcule, instead of coming 

 out. bury itself in the tube of the plant. He took it to be Botifer 

 vulgaris* 



In 1840, Meyen found it no less difficult than Morren had done, 

 to explain the introduction of the animalculae into the tubes of the 

 plant.t 



In 1853, the late Professor Hofmeister, in conjunction with 

 Professor Cohn, observed the filaments of a Vaucheria which had 

 pushed out short lateral club-shaped branches, in each of which 

 was a rotifer, which moved its cilia briskly. Hofmeister supposed 

 that the animalcule had penetrated into the tubes by piercing the 

 cellulose membrane without any damage to the plant. f 



In 1876, Dr. Magnus § observed in Vaucheria geminata whose 

 filaments were found floating in the ponds of the Thiergarten 

 (Berlin), numerous galls almost always laterally placed, in each of 

 which was a female of Notommata WernecJcii, surrounded with 

 eggs and newly-hatched young, which differed much in shape 

 from the mother. Observing that some of the old and empty galls 

 were perforated at the summit, Magnus supposed that the young 

 had escaped from these openings, whilst the mother remained inside 

 and soon died, exhausted by her numerous layings. 



Kiitzing fell into a similar mistake with Eoth, describing 

 V. geminata, whose filaments bear parasitic galls, under the name 

 of Vaucheria sacculifera, and mistaking the eggs of N. Wernechii 

 for zoospores. || 



We see, therefore, that beyond the specific determination of 

 the parasite, which we owe to Ehrenberg, we know very little of 

 N. Wernechii, either as regards its mode of reproduction, or the 

 details of its organization. This ignorance is doubtless owing to 

 the fact that N. Wernechii is almost always observed by botanists, 

 who naturally pay more attention to the plant than to its parasite. 



* " De I'existence des Infusoirea dans les Plantes," ' Bull, de I'Acad. de 

 Bruxelles,' 1839, vol. vi. p. 298. 



t "Wiegmann's ' Archiv fiir Naturgesch.,' 1840, vol. ii. p. 79. 



X ' Handbuch der Physiol. Botanik,' vol. i. ; ' Die Lehre von der Pflanzen- 

 zelle,' 1869, p. 77. 



§ ' Verhandlungen des botanischen Vereins der Provinz Brandenburg,' 18 

 Jabrgang, 1876, p. 125. 



II ' Tabula3 pLycologicfe,' vol. vi. p. 22, pi. Ixiii. fig. 3. 



