240 SUMMARY OF CURRENT RESEARCHES RELATING TO 



tlio surface of a Spongclia in disadvantageous circumstances. They con- 

 tained incipient tissue with undifferentiated cells, and had on section the 

 appearance of a very intricate network. It is suggested that they secure 

 the persistence of tho organism in unfavourable environment. 



Protozoa. 



Digestion in Rhizopods.* — Miss M. Greenwood has continued her 

 observations on the digestive processes in Amoeba and Actinosphaerium 

 with the following results : — 



(1) The ingestion of solid matter is promiscuous in Amoeba, that is, 

 nutritious and innutritious matters are taken in with equal readiness. 

 Actinosphaerium, on the other hand, rarely ingests innutritious particles. 



(2) The act of ingestion in Amoeba is accompanied by the emission of 

 pseudopodia ; in Actinosphaerium these may or may not be thrown out. 



(3) The nutritious matter taken in by Amoeba is not surrounded by fluid 

 when it lies in the endosarc. (4) Nutritious particles are in both animals 

 digested by fluid poured out around them. This fluid has no action on 

 the cuticle of organisms, or on cellulose or siliceous cell-walls. Fat and 

 starch are apparently not digested by it. It is a colourless fluid, which 

 acts on coagulated, and still more so on non-coagulated prote'id matter. 

 It has no action on litmus or carmine particles, accidentally inclosed 

 with nutritious particles, and is therefore neutral in reaction. (5) The 

 secretion is more active in Actinosphaerium than in Amoeba. (6) Chlo- 

 rojmyll is changed to a dark-brown colour by Amoeba ; this is not so 

 marked in Actinosphaerium. (7) Ejection is performed at the hind end 

 of Amoeba, either by means of a vacuole, or often without one. An 

 excretory vacuole is always present in Actinosphaerium. (8) The time 

 between ingestion and ejection is difficult to determine, and varies with 

 the size and digestibility of the ingesta ; it averages three to four days 

 in Amoeba. In Actinosphaerium the digestive act is shorter, and occupies 

 from H to 8 hours. 



Protozoa Parasitic in Man.j — Prof. B. Grassi emphasizes the 

 innocuous or purely commensal character of Protozoa found in man. 

 He discusses Amoeba coli, mono-cercomonads, JUcgastoma (Flagellate), 

 Balantidium coli, and disputes the Protozoan nature of Pfeiffer's Mono- 

 cyslis and of Plasmodium malariae. 



Psorospermium Haeckeli.J— Dr. 0. Zacharias has found the sporo- 

 zoon first noticed by Haeckel in the crayfish, in Silesian and Galician 

 specimens ; those that were examined seem to be quite healthy. The 

 parasites are of an elongated oval form, and are sharply separated from 

 the tissue of their host by a firm cuticle ; the long diameter is about 

 0-18 mm., and the breadth from 0-04-0-05. Several thousand may be 

 found in one crayfish, and it is not improbable that, if they increase too 

 rapidly, they may give rise to epidemics. They are much more common 

 in old than young individuals. When present they may be easily 

 detected in the eye, and it is likely that this is their way of entrance 

 into the body of their host. Dr. Zacharias has, however, been able to 

 show that the psorosperm is capable of multiplying within the body of 



* Journ. of Physiol., viii. (1887) pp. 263-87. Cf. Journ. Chem. Soc. Lond., 1888, 

 Abstr., p. 79. t Arch. Ital. Biol., ix. (1887) pp. 4-6. 



X Zool. Anzeig., xi. (1888) pp. 49-51. 



