302 



DESIGN IN NATURE 



direction for a certain period, usually a minute and a half, when it stops, and after a moment's pause reverses its 

 course, flowing the opposite way for about the same length of time, but rather longer in the direction in which the 

 mass is advancing. '^ It is by this means that the plasmodium creeps forward. The object of the onward move- 

 ment appears to be a search for food. If the yellow plasmodium of Badhamia lUricularis, wliich feeds on woody 

 fungi, is cultivated on Stereum hirswtum, placed on a plate, and covered with a glass shade, it extends itself over 

 the fungus with a turgid advancing border until it has devoured the more delicate hj^hse. Having exhausted the 

 nutriment, it will spread over the plate and the interior of the glass shade. If it is in sufficient quantity, it will, in 

 the course of a couple of days, cover the glass with a net-work of veins over an area of from forty to fifty square 

 inches. A piece of fresh Stereum, soaked in water, may now be inserted beneath the shade, allowing it to come in 

 contact with one of the smallest veins. In a few hours the whole of the plasmodium will have withdrawn from 

 the sides of the shade, and concentrated itself on the fresh food in a dense yellow mass. 



Fig. 59. 



Fig. 59. — A. Solerotium or dry state of Badhtimia utricularis, 



B to E. Plasmodium of Emilmmia utrindaHs. Shows advance of plasmodium on section of stem of Aiiariciis mellens 



ffi_ at 9 p \t V Si '' 



at 12.25 P.M. ; C. at 12.40 p.m. . D, at 1 p.m. : 



Illustrates the resting, inactive condition of the plant. 



f Plasmodium on section of stem of Ariaricus melleiis B. drawn 

 and E, at 2 p.m., x 3Jr. -^ > 



F. Young spores ot Badhamia utricularis, showing amosboid movement; the lower spore at right hand of figure changing its 

 shape m the course of a few minutes to that seen at extreme left of figure, x 565. 



G. Vegetable substance dissolved by plasmodium of Badhamia utricularis diminishing in size from left to right of figure taken 

 at mtervals of about a quarter of an hour, X 2.50 (after Lister). v^^ "gmc, oai^oii 



" The most remarkable activity of plasmodium hitherto witnessed was caused by a supply of Stereum provided 

 in a glass box. 



" There was at first, as not unfrequently happens, a shrinking backwards of the margin of the network of plas- 

 modium, as if notice of the presence of a food-supply had been sent off to the more distant parts ; then came on 

 a qmck stream of plasmodium, and in a quarter of an hour the whole side of the glass box was being covered with 

 astomshmg rapidity. The wide meshwork was not sufficient to conduct the abundant supply, and fresh veins started 

 off m all directions, cutting up the broad meshes. At one time the current along them all was so precipitate that 

 It was not possible to follow the course of the particles ; they rushed across the field of the microscope at a speed 

 that was truly amazing. ^ 



" It was a sight not soon to be forgotten ; the marvellous exhibition of such active life in so low an orcranism 

 was most impressive. ° 



1 TlR'se, to and fro moveniMits occur also in a considerable munber of plants, and in the circulation of the leecli, polyp, and other ] 



ow animal forms. 



