AN AQUATIC MTXOMYOETE. 65 



plant hung perpendicularly into the solution mentioned above ; in 

 this they developed vigorously, and were to all appearance quite 

 normal. During the course of the experiments, and while the plants 

 were exposed to the influence of the electric light emitted from incan- 

 descent Swann's lamps, certain minute black spots were several times 

 observed on the white roots hanging down into the liquid ; these spots 

 were all very small, but varied in size, and evidently increased in 

 number day after day and week after week, and beyond making a few 

 notes as to their occurrence and increase I paid little attention to them 

 at first, my interest being aroused in the progress of the more special 

 investigation to which my experiments were directed. Very soon, 

 however, the time came when it was necessary to examine the roots, 

 and their tiny black spots, and I then discovered that the little specks 

 were really the sporangia of a microscopic Myxomycete. Fig. 1 shows 

 the appearance to the unaided eye of the roots and the black spots 

 referred to, drawn to their natural size. 



In the first place their order of appearance showed no obvious 

 regularity with respect to either space or time. Sometimes one of 

 the tiny sporangia would arise at or near the tip of the root, at others 

 it would appear near the basal portion, or irregularly at any spot 

 between the base and apex. Again, while three or four might be 

 formed during a given 24 hours, none or several might make their 

 appearance during the next day, and so on. Moreover, I could detect 

 no obvious relationship between the order (or want of order) of suc- 

 cession, and any changes in the light (electric light) and temperature 

 which were noted with reference to my other investigations. All that 

 I was able to establish in this connection was that the black sporangia 

 became developed on the roots, both in the glare of the electric light 

 used, and in the diffuse daylight of January and February ; subsequent 

 investigation showed that they also became developed on the roots 

 when kept in the dark. The temperatures varied somewhat con- 

 siderably, and the sporangia were formed in some cases at 18° C, 

 during the periods when the electric light was turned on, and even at 

 14° or 15° C. during the night, and at those periods when the roots 

 were in the dark. 



Another point of interest is that by far the majority of the sporan- 

 gia referred to were developed in the nutritive solution — i.e. on parts 

 of the roots entirely submerged — though, as I shall show later, they 

 may also be formed on parts of the roots which are in the damp 

 F 



