196 PROTOPLASM. 



538. Protoplasm, the living matter of the plant, can be ex- 

 amined to advantage, either as it exists without a cell-wall in 

 some of the lower organisms (Myxomycetes), or confined within 

 a transparent cell-wall, as in 3'oung plant-hairs. 



539. The Myxomvcetes live in the interstices of moist porous 



/ *' 



substances ; for instance, decaying leaves and stems, spent tan, 

 etc. Passing over all details regarding their fructification, a 

 subject to be looked for in the volume on " Cryptogamic Botany," 

 their present examination can begin with the period when the 

 germinating spores of these plants rupture their walls, and 

 become confluent as masses of naked protoplasm known as 

 plasmodia. 



540. The plasmodium of ^Ethalium septicum is not difficult 

 to procure, as it occurs in summer upon heaps of moist tan in 

 the open air, and even during the winter in moist places in 

 greenhouses where tan is used as a stratum for flower-pots. It 

 is a soft, gelatinous mass of yellowish color, sometimes measur- 

 ing several inches in diameter. Removal of any portion of this 

 mass to a glass slide is apt to break up the plasmodium so much 

 as to render it useless for observation ; therefore the following 

 explicit directions given by Strasburger for obtaining small por- 

 tions to examine will be found useful. A tumbler is to be filled 

 with water up to the brim, and from the brim a strip of moist 

 filtering-paper, somexvhat less than an inch in width and one or 

 two inches in length, is to be stretched to the top of a glass slide 

 placed in a vertical position (or, better, leaning a little out- 

 wards) ; the lower end of the slide being placed in sand to catch 

 the water which will soon begin to flow slowly over its surface. 

 Next, a piece of bark with the plasmodium upon it is to be 

 placed at the foot of the slide, the whole covered with a bell-jar 

 and a dark cover of pasteboard, and from time to time the 

 water in the tumbler replenished. In the course often or twelve 

 hours some of the protoplasmic mass will climb up the slide in 

 the form of delicate threads, which branch more or less and con- 

 stitute a sort of network. The slide is then transferred to the 

 stage of the microscope, care being taken (1) to use only a 

 little light, and (2) to avoid any pressure by the cover-glass. 

 The latter may be prevented by fragments of glass placed under 

 the corners of the cover-glass; or, better still, the cover-glass 

 may be fastened on the slide by means of four minute drops 

 of cement, leaving its side exposed, and then the slide, thus 

 furnished with a cover, placed in the nearly vertical position Mi- 

 ready advised, when the plasmodium will creep under the cover, 



