2 A. E. HILTON ON THE FORMATION OF 



searched for Mycetozoa in the Highgate Woods. An old tree 

 stump to which I came was hidden by the leaves of branches 

 which had sprouted from it ; but on drawing the branches aside 

 I made a welcome discovery. Near the top of the stump were 

 the blackened remains of an old and leathery fungus ; and on 

 these sooty-black and fairly level platforms there were several 

 patches of milk-white plasmodium which appeared to have 

 oozed from the stump. The smallest patch was about 0*125 

 inch, and the largest about 1'125 inch in diameter; all being 

 probably portions of the same plasmodium, which had found 

 its way to the surface of the fungus by different channels 

 and in varying quantities. Carefully severing the fungus from 

 the stump, I transferred the treasures to my collecting-box. It 

 was on the stroke of noon, and I had found them only just in 

 time, as developments began almost immediately. 



The plasm was in a semi-fluid condition, and consequently 

 the patches were, at first, of a somewhat rounded and flattened 

 cushion-shape (PL 1, fig. 1). The surfaces soon assumed a frothy 

 appearance, and in about a quarter of an hour the cushions 

 were covered with bubble-like hemispheres, of uniform size, 

 somewhat translucent, close together, and slightly angled by 

 mutual pressure. In this condition they were charming objects, 

 resembling nothing so much as tiny blanc-manges, moulded 

 into perfect shape (PL 1, fig. 2). 



Here let us pause a moment to inquire what, so far, had really 

 happened. A simple question, but in biology everything is com- 

 plex, and of complicated phenomena only abbreviated accounts 

 can be given. Bear in mind that in the Mycetozoa, spore- 

 formation is essentially a process of rejuvenation by purifi- 

 cation. A Plasmodium about to form sporangia includes not 

 only its own proper nuclear elements and their cytoplasm, but 

 also an excess of fluid, and substances, more or less dissolved, 

 which have to be either secreted or excreted before this renewal 

 of youth can be effected. The excess fluid gradually evaporates, 

 and of the superfluous substances the cruder elements are 



