760 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Protozoa Parasitic in Man and the Diseases to which they give 

 rise. — In the second edition of R. Leuckart's well-known work* 

 on parasites we find an account of the Protozoa which inhabit man, 

 which is far more detailed than that of the first edition, and is com- 

 bined with an admirable exj^osition of the relations of the general 

 structure and the development of Protozoa generally, and specially 

 of the parasitic forms. The section embracing the Protozoa in- 

 cludes no less than 113 pages, and numerous original observations 

 made by the author are contained in it. The Schizomycetes receive 

 but brief notice, although the author " recognizes in their characters 

 scarcely a single reason for separating them from the Protozoa." As 

 Protozoa proper, the classes of the Bhizopoda, Gregarinida, and 

 Infusoria receive full attention ; hence it may be seen that Leuckart 

 attributes to the Gregarince, including the Psorosperrnice, the im- 

 portance of an independent class of the Protozoa, for which he 

 proposes at the same time the new designation Sporozoa. 



In the following account we shall limit ourselves to a short notice 

 of the parasites of man, which form the proper object of the work, 

 and only notice by the way the author's general ideas with regard to 

 the groups under review. The polythalamous forms seem to the 

 author to owe their origin to an asexual form of reproduction of the 

 Bhizopoda, if an expression of this kind is permissible, so that in 

 accordance with this view they may be set down as resembling the 

 colonies'of the Heliozoa and Padiolaria. This interpretation apjiears, 

 however, to be by no means a natural one, for the relations of the 

 nucleus, as set forth by R. Hertwig and F. E. Schulze, are not to be 

 reconciled with it. 



The Bhizopoda are represented as parasites of man only by the 

 pi'otean genus Amoeba, and but one species belonging to the grouiD is 

 satisfactorily known, viz. A. coli Losch, which was found m large 

 quantities in the stools of a Russian peasant who suffered from in- 

 flammation of the large intestine. Further observations render it 

 probable that the occurrence of this form is not so rare as has been 

 supposed. Whether we have here to do with a special parasitic 

 species or only with an occasional parasite — a question A\hich, of 

 course, owing to the protean character of most of the so-called species 

 of Amoeba hitherto described, can hardly be settled — Leuckart leaves 

 undetermined, but remarks on the resemblance which this form bears 

 to that described by Von Merescbkowsky as A. Jelaginia. Leuckart 

 considers that Losch's experiments on dogs prove the power of these 

 Amoebte, when occurring in large quantities on the mucous membrane 

 of the intestine, to cause hypera^mia and increased secretion of mucus 

 and even extensive inflammation. 



Of the Gregarince and their allies, the Sporozoa of his classification, 

 Leuckart gives a very full account ; tbey are treated of in their 

 general relations, both of organization and development, in so far as 

 these have been made known by the older and more recent investiga- 



* 2nd edition, vol. i. part 1 (Svo. Leipzig and Heidelberg. 1879). Cf. Zool. 

 Jahresber. Naples, I. (for 1879) pp. 117-21. Abstract with critical remarks bj 

 Prof. ButschU. 



