222 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the interesting question of contractile fibrils, it is pointed out that in 

 addition to those in the ectoplasm, first seen by van Beneden, there is a 

 fibrillation between the ecto- and endoplasm (A. Stuart). The question 

 of the mode of reproduction of the free Gregarines (i. e. of those not 

 parasitic within cells) is discussed at great length, under the following 

 heads: (1) Conjugation; (2) Encystation ; (3) Form of the cysts, 

 and characters of their envelope, in which is included a note on what 

 Schneider has called Pseudo-conjugation ; (4) Sporulation ; (5) 

 Further development and structure of the ripe spores ; (6) Develop- 

 ment of the contents of the spores ; (7) Development of Gregarines 

 from spores. 



The Sporozoa are divisible into the Gregarinida (S. Str.), Coccidia 

 (oviform Psorosperms), Myxosporidia (Fish-psorosperms), and Sarco- 

 si)oridia (parasitic tubes). 



Observations on Protozoa.* — A. Gruber commences by describing 

 some new forms ; of these Pachymyxa Jujstrix is a rhizopod of peculiar 

 organization, the larger specimens of which appear to the unaided eye 

 as small white granules ; this body is surrounded by an envelope 

 which consists of closely-applied fine rods, set nearly at right angles to 

 the surface ; destroyed by chromic acid and unaltered by osmic acid 

 their chemical composition still remains unknown. At any rate, they 

 are not foreign bodies, but secretions or products of the protoplasm. 

 Between the rods pores may be made out, and through these the pseudo- 

 podia may be protruded ; in form these are not lobate, but of equal 

 thickness, and of somewhat definite length ; they are never observed to 

 branch, and no streaming of the protoplasm was detected in them ; nor 

 do they seem to serve as locomotor but only as prehensile organs. 

 The protoplasm within appeared to be excessively viscid, and the only 

 structures that could possibly be regarded as nuclei were some red 

 dots, which may be small nuclei ; the relation, or possible relation, of 

 these to reproductive phenomena could not be studied. 



This remarkable form does not seem to be allied closely to any 

 known Protozoon ; in the formation of its pseudopodia it comes nearest 

 to Orhulinella; the envelope with its pores, reminds one of the perforate 

 Foraminifera, while the slightness in consistency and the form of the 

 pseudopodia, no less than the whole structure of the protoplasmic 

 body, indicates an alliance with the amoeboid Ehizopoda. 



After describing some naked masses of protoplasm found in the 

 sea-water of the same aquarium, the author passes to Amoeba ohtecta, 

 likewise found in the small marine aquarium ; small in size, it does 

 not creep about, but forms for itself a home of mucous substance, 

 which hardens in water, and becomes strengthened by the addition of 

 foreign bodies to its surface. Under suitable conditions, a number 

 become associated together, and appear to form a colony. 



After an account of Spongomonas gutiula n. sp., which likewise 

 seems to be colonial. Dr. Gruber discusses the characters of the genus 

 Stichotricha, a form of the Hypotrichous Infusorians, which is dis- 

 tinguished by the possession of a defensive envelope for its soft body. 



* Zeitschr. f. Wise. Zool., xxxviii. (1S83) pp. 45-70 (3 pis.). 



