336 SUMMARY OF CURRENT RESEARCHES RELATING TO 



fresh and from salt water. In regard to the interpretation of the life- 

 history, the author wholly rejects the suggestion that the ciliated em- 

 bryo indicates affinity with the Ciliata, and indeed denies that the 

 fundamental biogenetic law is applicable to the Tentaculifera at all. 

 The ciliated embryo he regards as adaptive, its ciliation being quite dif- 

 ferent from that of the Ciliata. He equally rejects the statement that 

 such forms as Peitiadia, Mesodinium, &c, show a transition between the 

 characters of the Ciliata and the Tentaculifera, and wholly denies the 

 existence of any affinities between the two groups. On the other hand, 

 he believes there is clear evidenceof affinity with the Heliozoa, and points 

 to similar nuclear phenomena (presence of a centrosome, chromosomes, 

 a spindle, and a spiral stage), to similar methods of reproduction (by 

 fission, by gemmas, and by embryos), to the similarity between tentacles 

 and pseudopodia, and to certain minor cytological peculiarities, as well 

 as to the slow movements and the slight specialisation of structure as 

 compared with the active highly organised Ciliata. 



Atlantic Tintinnodea.* — P. T. Cleve describes a small collection of 

 Atlantic plankton forms, and makes notes on the condition of the water 

 in which the specimens occurred. The collection includes a rare form 

 with porous house for which a new genus — Porella — is erected. Another 

 interesting form is Leprotintinnus brandtii (Nordquist) which was taken 

 off S. America, and has been previously described only in the Baltic. 



Alternation of Generations in Coccidium.f — Dr. Fritz Schaudinn 

 has made a long series of observations on the species of Coccidium which 

 infect Lithobius forficatus. In the grounds of the Zoological Institute 

 at Berlin, Lithobius is exceedingly common and is practically always 

 infected with the parasite, a fact which is no doubt due to the somewhat 

 confined space in which the hosts live. In the open woods, on the other 

 hand, only about 10 per cent, of the Myriopods were infected. Three 

 species of Coccidium occur in the host, and these are present in all com- 

 binations in the different individuals. No difficulty was experienced in 

 keeping the hosts in captivity and in infecting them with the different 

 species. The greater part of the observations were made on Coccidium 

 schibergi sp. n., which is rarer than the two other previously known 

 species, but is in some respects better adapted for study, and was obtained 

 in large amount by infection experiments. In this species the youngest 

 stage is a sickle-shaped embryo, which is capable of free movement, and 

 ultimately finds its way into on<3 of the cells of the gut of the host. Here 

 it grows at the expense of the cell, its nucleus divides up, and it ulti- 

 mately breaks up into a number of new sickle-shaped embryos which 

 infect the other gut-cells of the host. In the author's nomenclature this 

 process of asexual multiplication is known as schizogony, the mother- 

 cells are schizonts, and the daughter-cells merozoites. 



These merozoites, then, develope further in one of three ways : — 

 (1) They may grow rapidly, accumulate no reserves, and become con- 

 verted into schizonts; (2) they may become filler! with reserve food, 

 grow slowly, and become converted into female reproductive cells (macro- 

 gametes) ; (3) they may grow slowly but accumulate no reserves, and 



* Ofvf rs. af K. Vetensk.-Akad. Forhandl., 1899, pp. 969-75 (12 fisrs.). 

 f Zool. Jahrb., xiii. (1900) Abth. Anat., pp. 197-292 (4 pis.). 



