A. E. HILTON ON THE STUDY OF THE MYCETOZOA. 427 



My experienc? of this method leads me to believe that the 

 terms "dead leaves," "dead wood. - ' etc.. by which the textbooks 

 describe the habitat of certain species, must be understood in a 

 somewhat modified sense. Of course, the dead remains of 

 sporangia may be found on substances which are dead beyond all 

 doubt; but between full life and complete death there are grada- 

 tions, and it is quite likely that, while the sporangia were 

 developing, the substances on which they appeared were rather 

 in an intermediate state of decay than in a condition of absolute 

 lifelessness. It is at least feasible that the disintegrating plasm 

 of the vegetable host furnishes food for the plasmodium of the 

 Mycetozoa, and I find it better to choose substances which appear 

 to have some vitality rather than such as are utterly dead. 1 

 may here observe that sporangia, when dry, may in most cases 

 be preserved indefinitely, either in cardboard boxes or in dry cells 

 as microscopic slides. 



The present method of classifying the Mycetozoa is based, not 

 upon general features of sporangia alone, but chiefly upon the 

 colour, shape, and marking of spores, and the character of the 

 capillitia, the masses of fine threads or fibres in which the spores 

 are usually embedded. For examining spores and capillitia 

 objectives of at least |, and preferably | or T V in., are neces- 

 sary ; but the system founded on these minute characters is not 

 wholly satisfactory, because there are many variations, and the 

 images obtained by means of the microscope are often difficult 

 of interpretation. The swarm -cells also require a high magni- 

 fication, say 600 diameters ; and the continuous development of 

 these can be observed by the method knowm as " hanging drop " 

 cultivation, described by Dr. Karop on page 265 of the Quekett 

 Journal for April, 1902. 



In my opening remarks I referred to the streaming movements 

 of plasmodia. These are singularly striking. When a Plas- 

 modium is sufficiently large and on the surface of its host, and 

 the plasm is sufficiently free from discolouring matter to be 

 transparent, the interior nuclei, vacuoles, and granules are seen 

 to be flowing, with a rapid, alternate, rhythmic motion, along the 

 principal channels of a network of veins, into which the plas- 

 modium spreads itself as it slowly creeps about in search of food. 

 The flow continues in one direction for a minute and a half or 

 two minutes; then pauses, immediately reverses its course, and 

 flows back again. The streaming in the direction in which the 

 Plasmodium is creeping is slightly stronger than the streaming 



