10 MYCETOZOA 



six to nine hours without any apparent alteration ; at the 

 end of this time a slow amoeboid change of outline is observed, 

 sometimes accompanied by the projection of numerous pointed 

 pseudopodia. The four nuclei now divide by karyokinesis. A 

 constriction appears in the middle portion of the cell, followed 

 by a second constriction in each half. The first division 

 may now become complete, but usually the whole of the spore 

 contents remain united until a further constriction takes place 

 in each quarter, and in about an hour from the time when 

 the first movement was observed the originally ellipsoid body 

 is divided into eight spherical portions, each containing a 

 nucleus. These portions occasionally become free at this 

 stage, but as a rule they continue attached to one another by 

 narrow bridges ; a few minutes later each protrudes a flagellum 

 and assumes the pyriform figure of a swarm-cell ; then by the 

 united lashing movement of their flagella the cluster of eight 

 swarm-cells swims away (fig. 4). They may remain connected 

 for an hour or more, but eventually become detached, and 

 resemble the swarm-cells of the Endosporeae as above described. 

 The swarm-cells have been observed to piss into the amoeboid 

 stage, as in the Endosporeae, but the fusion of these amoebae 

 to form a plasmodium has not been directly observed. 



The Plasmodium. — Several of the phenomena which are met 

 with in the swarm-cell may be seen in the plasmodium on an 

 extended scale. Like the former when in the amoeboid phase, 

 it is endowed with power of locomotion, and advances over the 

 substratum with a creeping movement. The interior sub- 

 stance consists of granular protoplasm, containing numerous 

 nuclei and vacuoles. The latter vary in size, and are often 

 seen to contract and discharge their contents, which are either 

 watery or contain refuse matter. The movements in the 

 interior of the swarm-cell are extended into a systematic circu- 

 lation in the plasmodium, which spreads in a network of veins 

 with a few principal channels. Through these the granular 

 substance streams in a rapid torrent which gradually comes 

 to a pause in the space of a minute and a half to two minutes, 

 and then immediately reverses its course. A rhythmic flow 

 is thus maintained backwards and forwards at nearly equal 

 intervals, but always of somewhat longer duration in the 

 direction in which the plasmodium is creeping. The flow is 

 continued from the larger to the smaller veins which branch 

 with increasing intricacy till they are lost in the broad tumid 

 margin of the advancing plasmodium (see Frontispiece). The 

 whole is invested by a layer of hyaloplasm devoid of granular 

 particles, but merging imperceptibly into the inner stratum. 

 The hyaloplasm exhibits amoeboid movements, projecting and 

 withdrawing pseudopodia, and is unequal in thickness over 



