252 SUMMABY OF CURRENT RESEARCHES RELATING TO 



as the protoplasm round them becomes very granular, and a vacuole appears 

 gradually after ingestion. The action on shielded proteid was the same as in 

 the case of Ainoiha. As an exam])le of "unshielded proteid," the digestion 

 of a small Crustacean larva was observed ; after eight hours its shape had 

 been lost, and a vacuole had a]>peared. An Euglenoid form continued to 

 struggle for 2^ hours, but after 15 hours was disintegrated, though green 

 colour remained. All ■ jecta are passed out by means of a vacuole. There 

 is probably some difference in the process of digestion in Amoeba and 

 Adinosphxrium. 



The means by which the digestive changps are brought about. — Direct 

 contact with the protoplasm is not necessary, so that the " secretion of some 

 digestive fluid " must take place in the vacuole in Amoeba. Innutritious 

 material does not act as stimulus to the secretion ; and ejectiun is in this 

 case unaccompanied by any " viscid fluid." As to the nature of the digestive 

 fluid, no very definite result is arrived at. Blue litmus remained unchanged 

 for several hours. Methyl-violet and tropaeoliu were unsuccessful. But 

 probably the secretion is not acid. 



The paper concludes with a tabular statement of the changes observed 

 continuously during the action of ingestion and digestion : (A) in Actino- 

 sphserium for ten hours ; and (B_) in Amoeba for nine days. 



Multiplication of Leucophrys patula.* — M. E. Maupas states that 

 Leucojyhrys patula grows very rapidly, owing to its powerful buccal appa- 

 ratus enabling it to be a voracious and successful carnivore. Its growth 

 and its power of fission are in relation to this power of absorption — indi- 

 viduals isolated and placed in a rich medium divide four or five times a 

 day, that is to say, one individual gives rise in twenty-four hours to thirty- 

 two descendants. When, owing to its abundant multijilication, it has used 

 up the great quantities of food at its disposal, this infusorian undergoes a 

 series of remarkable and unique changes. 



The individuals fix themselves to the edges of the drop of water in 

 which they are living, and roll themselves up into a ball, as if they were 

 going to encyst, but they form no cyst ; the buccal apparatus disappears 

 entirely, and the mouth is merely indicated by a shallow groove, which is 

 difficult to detect ; they then begin to undergo transverse division, but do 

 not move nor eat afterwards ; the divisions succeed one another rapidly, so 

 that in a few hours each Leucoinhrys gives rise to sixty-four individuals. 

 These take on an oblong cylindrical form and begin to move about ; they 

 are only 60 fx long and 19 to 20 /x broad, while their parents were 150 /x 

 long and 100 yu, wide. Had not their direct descent been observed it would 

 be impossible to believe that they were derived from their parents, so 

 different are they in all their characters. 



For several days they exhibit great mobility, and are for the most part 

 eaten up by the contemporaries of their parents who have not undergone 

 division ; later these latter do so. The products of division which have 

 escaped being eaten by their relatives again become immobile, and during 

 this period of rest they take on the typical form of the Leucophnjs and 

 re-form their buccal apparatus ; when food is given them they absorb it at 

 once, and rapidly grow up to the normal size of the species. No process 

 of conjugation was, it is to be noted, observed at any stage. It would seem 

 as if we had here to do with a species which preserves itself by autophagy. 

 The observations of Claparede, Stein, and Balbiani on the dwarf forms of 

 Stentor cseruleus may perhaps receive their explanation from the account 

 here given. 



* Comptes Rendus, ciii. (1886) pp. 1270-3. 



