468 SUMMARY OF CURRENT RESEARCHES RELATING TO 



certain that their occurrence is not to be associated with any develop- 

 mental phenomena. 



In a i)ostscript reference is made to tlie lately published work of 

 Entz,* who demos the accinacy of Gruber's statenicnts ; it is pointed 

 out that Gruber's observations were of long duration, whereas con- 

 jugation takes but a short time. 



The author justly remarks that a new field of difficulty in the 

 investigation of the Protozoa is being opened out to us. 



Peridiniae. f — Dr. G. Klebs has investigated the structure of the 

 palagic Peridinife, driven into the Gulf of Naples by a strong sirocco. 

 Only a few forms are found along the coast among the lower algaj. 

 The marine ally themselves nearly to the fresh-water forms. 



The body is usually divided by a transverse furrow into an anterior 

 and a posterior half, the two halves being either equal or unequal, 

 the posterior half usually provided with a longitudinal opening into 

 tlie transverse farrow. The superficial structure of the membranes 

 which give a cellulose reaction varies greatly. While in the young 

 state the membrane is quite smooth ; spines, projections, &c., aro 

 formed at a later period, the membrane becoming at the same time 

 brittle, which leads to a breaking up of the shell. This usually 

 takes place very regularly, so that the membrane appears to consist 

 of several plates, the number of which is not always constant, and 

 therefore not of the importance attributed to it by Stein. The cause 

 of the brittleness is not known. From the faet that the structures of 

 the cell-wall are gradually formed, it results that they must not be 

 relied on exclusively for the diagnosis of the species. The author 

 adduces as an instance Glenoclinhim trochoideum. 



The peculiar structure of the membrane of species of Ceratlum is 

 then described in detail. In addition to this, the mode of ciliation is 

 characteristic. Although Stein, Goi-rret, and Pouchet maintain the 

 existence of a whorl of cilia, Klebs finds, in the marine as in the 

 fresh-water Peridinife, only a single cilium in the transverse furrow ; 

 this is especially evident in Amj^hidinium opercnlotum. The cilium is 

 here coiled round the anterior part of the body ; the second cilium, 

 directed backwards, has its insertion near the first ; it is stretched out 

 at length during movement. The author enumerates the species in 

 which these cilia have been distinctly observed. In regard to the 

 second cilium, he confirms the observations of Claparede, Lachmann, 

 and Pouchet. 



The internal organization of the marine and fresh-w^ater Peridini® 

 is very similar. There is always a nucleus, aid its structure is very 

 characteristic. It contains parallel nuclear thrt-ads, which separate 

 into distinct rods when laid in water. No nucleolus could be detected 

 in species of Ceratium, nor in Glenodinium ohliqitum. The peculiar 

 structures taken by Stein for germinal globules are widely distributed, 

 but the author is unable to ftate anything with certainty with regard 



* Sec this Journal, ante, p. 80. 



t Bot. Ztg., xlii. (1884) pp. 721-33, 737-45 (1 pi.), f^ce this Journal, iv. 

 (1884) p. t.i8. 



