640 SUMilAKY OF CURRENT RESEARCHES RELATING TO 



sequently becomiBg fixed and producing a fructification of various 

 forms. Less often (hitherto known only in the case of Giittulina rosea, 

 as described by Cienkowski) the myxamoebaB simply aggregate without 

 fusing ; no plasmodium is formed in the strict sense of the term, but 

 only a mass of naked cells capable of gliding one over another, out of 

 which the fructification is formed, each cell giving birth, within this 

 fructification, to a spore or a " foot-cell." To the first of these kinds 

 of Plasmodium M. Van Tieghem gives the name fused (fusionne), to 

 the second aggregated (agrege), and details a considerable number of 

 fresh observations respecting the latter, including the description of a 

 new genus and of four new species. 



Acrasis n. gen. {A. granalata n. sp.). On beer-yeast exposed in a 

 pasty layer black spots appeared which proved to be constituted as 

 follows. An erect filament consisting of a single row of cells, termi- 

 nates in a bunch of spherical brownish- violet spores, the cell- wall being 

 covered with small elevations. The spores have a diameter of about 

 O'Ol to 0'015 mm., and are often unequal in the same bunch. The 

 inferior cell of the filament is dilated at its base into a palmate spur. 

 Cultivated in fresh urine, the cell-wall ruptures, and there escapes a 

 protoplasmic body without nucleus. Spherical, and at first motionless, 

 this body soon becomes endowed ■with an amceboid motion, increasing 

 at the same time, and subsequently dividing in two. This bipartition 

 is sometimes effected by a constriction while in motion ; more often 

 the myxamoeba first reassumes its spherical form and its immotility, 

 and then divides, the two halves becoming rounded off as they sepa- 

 rate, and recommencing their changes of form and their power of 

 movement. This process of bipartition proceeds until a large number 

 of myxamoebfe are thus formed. 



A new phase then commences. Here and there, usually at points 

 situated at the periphery of the nutrient fluid, a larger or small num- 

 ber of the myxamceb^e approach one another, round themselves off, and 

 form a small cellular mass. In each of these groups, the size of 

 which is very irregular, the elements, although closely aggregated, 

 remain completely independent and capable of moving over one 

 another, in consequence of which the mass raises itself perpendicularly, 

 and forms in the air a cone which becomes gradually longer and 

 thinner. The cells of the axile row, one and a half times or twice as 

 long as broad, first develope a cell-wall of cellulose, and form the 

 " foot." Along this solid axis the external cells glide and raise them- 

 selves, assuming a spherical form, and becoming invested with cellu- 

 lose, thus forming a longer or shorter bunch of spores. The cell-wall 

 of the spores then becomes cuticularized and covered with small ele- 

 vations, and assumes a dark violet colour; the fructification thus 

 attaining its definite characters. The number of spores in the fructi- 

 fication and the length of the foot vary greatly, according to external 

 circumstances ; and occasionally the fructification is of a somewhat 

 more complicated character. If, during the period of growth and 

 bipartition, the conditions become unfavourable, the myxamoebaB 

 become rounded off and encysted, increasing then by a kind of 

 budding. 



