NOTES AND MEMORANDA. 95 



tractile vesicle. Engelmaun found that a posterior circlet of cilia 

 was developed in the infected Vorticclla, which then swam away, but 

 in the cases observed by Eees, the Vorticclla drew itself together and 

 sometimes became encysted. In one case quite an Endosphcera epidemic 

 was observed. 



2. Vorticella campamda. — Amongst normal individuals some 

 specimens Avere seen containing large, strongly refracting spheres, 

 exhibiting a single contour, granular contents, and a dark, strongly 

 refracting, spherical or oval nucleus ; no contractile vesicle was ob- 

 served. Each Vorticella contained from two to eight of the spheres, 

 the size of which was inversely pi'oportional to their number, but 

 usually constant for each infected specimen. In one case, however, 

 one sphere was decidedly larger than any of the other in the same 

 specimen, and had two nuclei, whence it is inferred that multiplication 

 takes place by division within the body of the host. The further fate 

 both of host and parasite is unknown, and no opinion is advanced as 

 to the nature of the latter. 



3. Oxylricha faUax. — The appearance presented by the infected 

 individuals in this case, seemed, at first sight, to lend great support to 

 the theory that the nucleus is a germ-producing organ. The parasite, 

 to which, as in the preceding case, the author gives no name, occurs 

 within the nucleus of Oxijtriclia, in the form, at first, of minute 

 spheres, which are, except in the case of the smallest of all, nucleated, 

 but are devoid of a contractile vesicle. In further stages the spheres 

 increased greatly in size, and exhibited a distinct cell-wall, and under- 

 went multiplication by fission. In the latter process the cell-wall 

 took no part, and the division masses did not at first round themselves 

 ofi'. The nucleus of the Oxijtriclia became, of course, greatly altered 

 in shape, and in the final stages usually disappeared. The spheres 

 either escaped through an aperture in the substance of their host, or 

 were liberated by its disintegration. In either case, the daughter- cells 

 of spheres which had undergone division, rounded themselves oif, after 

 being liberated, and exhibited slow movements, due, the aiithor thinks, 

 to very minute cilia, which he believes he was able to see in some 

 instances. After a time the movements ceased, and the daughter-cells 

 were gradually transformed into a granular mass, devoid of any trace of 

 cell-contours. The author seems to think it probable that the cell- 

 colonies thus formed divide into single cells, and that these latter, or 

 the products of their division, finally penetrate into the body of 

 Oxytricha fallax. He believes the parasite to be one of the lower Algce. 



Microscopy at the American Association for the Advance- 

 ment of Science. — At the meeting of this Association, to be held in 

 August, 1879, Professor E. W. Morley, of Hudson, Ohio, will be the 

 Chairman of the sub-section of Microscopy. 



Germination of the Spores of Volvox dioicns. — Although the 



' Journal de Micrographie ' says that ' All microscopists are acquainted 



with the work of Cohn on Volcox glohator,' * we believe we are correct 



in saying that very little was known of it in this country until t]]e 



* 'Beitrilge ziir Biologie tier Pfliaizen,' vol. i. pait3, 1875. 



