900 RECORD OF CURRENT RESEARCHES RELATING TO 



which is specially remarkable for the attacliment to it of a clelicato 

 membrane which arises from the hinder part of the animal, and is 

 able, when the animal contracts itself, to shut down the operculum of 

 the shell. 



Influence of the different Colours of the Solar Spectrum on 

 Infusoria.* — Senor Serrano y Fatigati has instituted experiments on 

 this subject with results agreeing with those of M, E. Yung t in the 

 case of the ova of frogs, fish, &c., viz. that the violet rays accelerate 

 and the green rays retard the development of Infusoria. 



Supposed new Fresh-water Species of Freia. — See ' Proceedings,' 

 p. 989. 



Lithamoeba discus, a New Rhizopod. — This interesting form is 

 described by Professor Eay Lankester,| who discovered it in some 

 water sent him by Mr. Bolton from the Olton Eeservoir near 

 Birmingham. 



The body is discoid, and has a diameter of y-|g inch. In the pro- 

 toplasm of which it is composed are imbedded a great number of 

 highly refracting, often uniform, concretions, the largest of them yi^ 

 inch in length, but most of them not more than a quarter of that size. 

 The composition of these curious bodies was not made out ; they were 

 not affected by dilute acetic acid or potash, but were dissolved by strong 

 hydrochloric acid. Probably they are of similar nature to the 

 granules of Amceba. 



There is a single large nucleus, ^^ inch in diameter, of an irre- 

 gularly trapezoidal form, and enclosed in a distinct membrane. It 

 consists of a ground-substance, with a number of angular granules 

 imbedded in it. 



Included food materials — diatoms, &c. — were observed in the pro- 

 toplasm, the centre of which is occupied by a very large contractile 

 vacuole ^\q inch in diameter ; a portion of the contents of this " are 

 discharged periodically to the exterior." The vesicle does not entirely 

 collapse, but divides into two smaller ones, which afterwards enlarge 

 and fuse together. 



The protoplasm exhibits a distinct vacuolar structure, especially 

 well seen by treatment with osmic acid and picro-carmine. In this it 

 resembles Greef 's Polomyxa. 



The application of iodine brings out the presence of a fine cuticle, 

 so fine that it is ruptured by the extrusion of the pseudopodia. These 

 are very interesting : their protrusion begins " with a minute rupture 

 of the cuticle. Through the orifice thus produced the fiuid proto- 

 plasm exudes in a spherical form, and as it increases in quantity the 

 rupture of the cuticle is increased, whilst concretions from the more 

 central portion of the disk-like body flow into the enlarging lobe. 

 With great rapidity the whole extrusion appears to fuse once more 

 with the disk, and a new rupture or extrusion takes place at another 

 point of the margin. A new cuticular pellicle must be formed very 



* ' An. Soc. Esp. Hist. Nat.,' viii. (1879) (Actas) pp. 42-3. 



t This Journal, ante, p. 138. 



X ' Quart. Journ, Micr. Sci.,' xix. (1879) p. 484. 



