8 A. E. HILTON ON CAPILLITIA OF MYCETOZOA. 



nucleated plasm-speck clothes itself with a protective envelope, 

 and becomes a complete and separate spore. 



The recognition of this coincidence between successive 

 bipartitions of the plasm, and the progressive formation of a capil- 

 litium along the chief lines of cleavage and contraction, is a 

 long step towards a comprehension of the more obvious features 

 of the capillitia of Mycetozoa; but it is not possible, even if 

 it were desirable, to determine in detail the processes by which 

 the minuter characteristics of the threads are brought about. 

 Shrinkage in drying plays a conspicuous part ; but the more 

 obscure forces at work belong to the order of molecular physics. 

 The results are variable. "It is an open question," remarks 

 Mr. Massee, " as to whether ornamentation of the capillitium 

 threads is of generic value, even if constant, as supposed by 

 Rostafinski, but such is certainly not the case." * 



About the middle of October 1915 a good gathering of rising 

 sporangia, found on a tree-stump near the Cockfosters end of 

 Hadley Woods, gave me a rare opportunity of watching the 

 development of Lamproderma columhinum. When discovered 

 at 2.30 p.m., the sporangia were about l/8th inch high. The 

 plasm was watery-white and transparent, and at the base of 

 each sporangium a stalk was beginning to show. By 5.30 p.m. 

 the sporangia were turning colour, becoming slightly brown and 

 less transparent. At 7.0 p.m., under the microscope, a capillitium 

 could be made out ; and during the next hour or so this pro- 

 gressed considerably, branching and rebranching in a curiously 

 intermittent way, and growing finer and more delicate as it 

 proceeded. To look at, the process was singularly like the 

 growth of a crystal by rapid but discontinuous accretions in a 

 supersaturated solution ; and similarly, the precipitation in 

 this case was doubtless due to evaporation of moisture. By this 

 time, although the plasm was still fairly transparent, its outer 

 surface was becoming wrinkled by the escretion of a mem- 

 branous sporangium wall ; and the later development of the 



* A Monograph of the Myxogaatres, by George Massee, 1892, p. 14!^ 



