802 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Nuclei of Lieberkuehnia.* — This fresh- water rhizopod was first 

 described by Claparede and Lachmarin, and afterwards by Cienkowski, 

 under the new name of Gromia paludosa. The observations of these 

 authors are, however, E. Maupas considers, far from being com- 

 plete ; and, moreover, are erroneous in some essential points. 



The form of the body is variable, and may be perfectly spherical, 

 ovoid, oblong, or even fusiform. Each individual can assume all 

 these forms ; and when the same specimen is under observation during 

 several days, it is seen to pass through all these changes. These 

 changes take place very slowly. The carapace is very transparent, 

 and is closely applied to tbe surface of the body, and changes with it. 

 It also shares in the fissiparous division. It cannot, therefore, be 

 regarded as a true carapace, like that of the Arcellce and the Difflugice, 

 where the carapace is a product of chitinous secretion of the nature 

 of a skeleton, and has a very different morphological value. In 

 Lieberkuehnia the seeming carapace is in reality only an integument 

 or ectosarc, which can be isolated by certain reagents from the 

 endosarc. 



The pseudopodia are capable of extending to a length of 2 ■ 26 mm., 

 the body of the animal having a diameter of from - 15 to 0'16 mm. 

 The circulatory movement of the sarcode is one of the most rapid yet 

 observed. The granules move through a space of • 66 mm. a minute. 

 The Infusoria which strike the meshes of their network are rendered 

 motionless, and in this way LieberJcuehnia is able to capture large 

 Infusoria, such as Paramecium aurelia. Sometimes the Infusoria are 

 swallowed whole ; sometimes the sarcode of the pseudopodia envelopes 

 them on every side, and constitutes around them a digestive vacuole, 

 in which they are dissolved outside of, and frequently at some distance 

 from, the body. They do not reach this till later on, when they are 

 already assimilated to the substance of the pseudopodia in whose 

 circulatory movement they disappear. The digestion takes place, and 

 is finished, entirely outside of the body. With small Infusoria, such 

 as Cyclidium glaucoma, the operation hardly lasts five or six minutes ; 

 but Paramecium aurelia resists more than an hour. The sarcode of 

 the mass of the body is in constant motion, not regularly in the same 

 direction, like the cyclosis in Paramecium aurelia, but split up into 

 currents with varying directions. This sarcode is hollowed out by 

 numerous vacuoles of different volume and size, which are carried 

 along by the currents, in which they are often seen to change their 

 form, and sometimes to amalgamate one with another. They always 

 end by coming to the periphery of the body, where they contract in a 

 similar manner to that of the so-called contractile vacuoles. Lieber- 

 kuehnia is therefore not, as has been stated, destitute of these organs 

 of excretion. It is, on the contrary, perhaps more richly furnished 

 with them than many other Protozoa. There is simply this differ- 

 ence, that the contractile vacuoles are neither permanent nor localized 

 in any region of the body, every part of which may serve as a basis 

 for their formation. 



* Comptea Kendus, xcv. (1882) pp. 191-4. Ann. aud Mag. Nat. Hist., x. (1882) 

 pp. 410-13. 



