22 PROFESSOR P. MARTIN DUNCAN. 



mentioned had its top slightly beyond the level of the inter- 

 cellular wall of the first process. The opaque spot had in- 

 creased in size, and there were two places where the outer 

 line of the cell- wall was in its normal curve, Avhilst tlie inner 

 was sharply bent inwards, so as to encroach on the interior of 

 the cell (b ). Both were in the immediate neighbourhood of 

 the opaque spot, the longest of the two bounding it below. 



In a second quarter of an hour the longest of the bends 

 had reached across the cell in a slanting direction, and had 

 united with the opposite wall (b"). The smaller curve had 

 increased so as to separate the lines of the cell- wall for some 

 distance, and the opacity had diminished. The top of the 

 cell was further in advance of the intercellular wall of the 

 first process. 



In the third quarter, and at the expiration of three quarters 

 of an hour from the beginning of the observations, the new 

 cell-top had grown far in advance, and had become very 

 considerably rounded {b'"), whilst slight irregularities in the 

 direction of the inner line of the wall were noticed in it and 

 also in the lower cell. 



During this lapse of time the first process (fig. 1) had 

 grown in length, and the distal cell {a) had altered con- 

 siderably in its details. The curve in the inner line of 

 the cell-wall had diminished, but a large and conical one 

 had reached the opposite cell-wall, thus forming a dissepi- 

 ment and dividing the cell into two {a"). Moreover, irregu- 

 larities in the contour of the inner wall existed in the 

 opposite side to those just noticed ; the refractile granules 

 were not so numerous, and the whole cell had increased in 

 breadth as well as in length. The so-called curves could be 

 noticed to change their form by a slow undulating move- 

 ment, which was singularly suggestive of the method of 

 movement of Amceba, and it was evident that the motion 

 extended beyond the curve amongst the more mobile included 

 protoplasm. There was no trace of gas bubbles around the 

 cells, and the elongation, increase in bulk and the molecular 

 changes were not attended by any visible chemical action. 



The impression left on the mind was that the cell-wall 

 was merely a more solid condition of the protoplasm of the 

 cell, and that the movement was determined by portions of 

 it returning to their more fluid state, owing to the transmission 

 or absorption of the surrounding medium. 



Could one of the cells have been removed from the contact 

 of the others, it would have greatly resembled a Protamoeba 

 in movement within a homogeneous tissue. Movements 

 lite these are not observed in most algae which are 



