392 MKS. L. J. YELEY CONTKIBUTION TO THE 



chance of survival under unfavourable conditions, or in a 

 diminished supply of water, than a single large one. Large 

 individuals have a tendency to burst, and I am in agreement with 

 Penard's latest view (1902) that this is a quite frequent and normal 

 occurrence, and not due to surface tension or damage. Once, 

 in the whole course of the investigations, a single torn and 

 damaged Pelomyxa, " planted " in a flask of egg-albumin 

 stoppered with sterilized cotton-wool, gave rise to a very large 

 number of amoebae, each possessing a single nucleus and con- 

 tractile vesicle ; but as this production unfortunately did not 

 take place under actual observation, the fact only can be recorded. 

 Such observations have been made before, by GrreefF and 

 Korotneff, but in view of their scarcity, and the fact that they 

 have never received general acceptance, it seems worth while to 

 note this, and also to mention that the circumstances excluded 

 all possibility of any other origin for the amoebae, with which 

 the liquid literally swarmed. Penard has noted a similar occur- 

 rence, since G-reeff and Korotneff. One other curious point 

 must be recorded. Section liad been made of two Pelomyxcs 

 into two pieces each, and these four fragments A\ A^ of one 

 individual, B\ B^, of another, were watched under the microscope 

 in one field, those belonging to one individual being kept on the 

 left, the others on the right. (This was being done with a view 

 to observing whether the ragged pieces rounded up again as 

 separate individuals, as noted by Penard for Difflugia.) A^ 

 constricted off a further piece A^ ; A^ after complete separation 

 from A\ made independent movements, and in so doing 

 approached B'. 



A^ and B^ came into contact, and A* immediately fused with 

 B\ becoming in a few moments quite indistinguishable from it 

 (PI. 38. figs. 22-24). A similar behaviour of fragments has been 

 recorded by Penard for Uiffltigia, but he expressl}' stated that, 

 while a fragment readily fused with another recently severed 

 fragment from the same individual, no such thing ever occurred 

 betvi'een fragments from different individuals. 



This observation with regard to Pelomyxa appears, tlierefore, 

 to be new, and may possibly have considerable significance, since 

 it raises the old question whether Pelomyxa can ever justly be 

 regarded as a single individual. Of course it may simply mean 

 that the protoplasm of Pelomyxa is chemically homogeneous to 

 an extraordinary degree ; but, on the other hand, if fusion of 



