IN THE PLASMODIA OF MYCETOZOA. 267 



My answer to this is, that a patient examination, under a 

 microscope, of a plasmodium of B. utricularis leads to discoveries 

 which, for the sake of brevity, may be formulated thus : 



(a) The streaming movements in the finer threads of the 

 network are controlled by the stronger currents in the coarser 

 veins. 



(6) The main currents in the principal veins, in their alter- 

 nations, always radiate from, and converge towards, more or 

 less definite centres consisting of larger or smaller aggregations 

 of plasm. For example, a fanlike expansion receives its impulses 

 from the mass with which it is connected, and from which it 

 protrudes. The general direction of the streams is from the 

 base to the advancing border ; and from the border to the base 

 when the current is reversed. 



(c) If a fanlike extension is severed from its base, at what 

 we may call the isthmus of attachment to the plasm mass which 

 feeds it, the impulse controlling the circulation is temporarily 

 lost. The streaming instantly diminishes, and what is left is 

 disorganised ; the remaining streamlets being feeble, disconnected, 

 and out of harmony. On the other hand, if a piece is cut from 

 the margin of the fan, the base of attachment being left intact, 

 the circulation in the fan is but little affected. 



(d) In the excised portion of a plasmodium recovery of cir- 

 culation may come about by the denser portion of its mass 

 becoming dominant, and controlling from this fresh centre a 

 new system of currents spreading through the more extended 

 parts. 



(e) If two plasmodia of the same species, or, which is the same 

 thing, if two separated portions of one plasmodium, come into 

 contact and coalesce, the separate systems of circulation at first 

 conflict, but gradually combine into a circulation common to 

 the whole, as either one or other of the two main centres of 

 impulse gains predominance. 



(/) Contrariwise, it sometimes happens that in a single 

 plasmodium more than one mass controls the streaming move- 

 ments, each exercising an influence over a certain area, but 

 unable to control the rest ; and unless harmony be re-established 

 this results in severance at the limits of control, the one 

 plasmodium becoming two or more, by reason of each head- 

 centre commanding a certain following of the extended plasm. 



