and Laboratory Methods. 11-1 



also the formation of new branches by the coalescence of the pseudopodia can 

 be observed. It will not be necessary to go into further details, for I have 

 nothing new to add to the general description given in the English edition of 

 DeBary's Comparative Morphology and Biology of Fungi, Mycetozoa, etc. (p. 

 425) ; all that is spoken of there can be readily seen and followed. In fact, 

 for laboratory demonstration of the streaming movements of protoplasm to 

 beginners, this plasmodium has proved of far more use than the Amoeba or the 

 other objects usually used, as Chara tips, Tradescantia hairs, etc. ; because, 

 being macroscopic in size, you waste no time finding it, and not having any 

 very dense cell walls, at the ends of the network at least, the motion of the proto- 

 plasm can be clearly seen ; besides, being able to put one's hands on it any time 

 one wishes is not the least of its advantages. 



If the water is allowed to evaporate, the course of the plasmodium, following 

 the surface of the water, can be easily traced by the " envelope " of DeBary, or 

 the " hypothallus " of Miller, which remains behind, and the outlines of which 

 are accentuated by the refuse gathered around it, as shown in Fig. 3. 



Permanent mounts of plasmodia may be made by plunging the slides upon 

 which they are spread into strong alcohol, or a solution of picric acid in strong 

 alcohol. The alcohol seems to be necessary to coagulate the albuminous sub- 

 stances, and so fix the plasmodium to the slide at the same time that it is killed. 

 If aqueous killing fluids are used, such as picro-sulphuric or corrosive acetic, a 

 considerable evolution of gas is seen to arise from the plasmodium (probably 

 CO 2 from the CaCOj), and sooner or later it floats down from the slide, and 

 it is difficult to successfully remount it. With the alcohol the most delicate 

 threads remain intact. The slides may then be transferred to some aqueous 

 stain (Griibler's haematoxylin gave good results), and if desired the stain may 

 be differentiated with acid alcohol without harm. The vacuolated structure of 

 the protoplasm is very beautifully shown, but it is difficult to distinguish between 

 nuclei, ingested food particles, or refuse composed of unicellular organisms, 

 bacteria, etc., which sticks all over the plasmodium. This last difficulty might be 

 largely obviated, I should think, if Miller's directions on the Aseptic Cultivation, 

 etc., were carefully followed. Bacteria, according to Miller, are always present, 

 but they would be easily distinguished. Clara Langenbeck. 



Wells College. 



MICRO-CHEMICAL ANALYSIS. 

 X. 



POTASSIUM— Continued. 



VI. IVit/i Stannic Chloride. 



The hydrated stannic chloride is employed, since this hydrated salt is much 

 more easily handled than the anhydrous liquid compound SnCl4. In the 

 hydrated salts SnCl4;cH20, x may be either 3, .5, or 8. All three of these salts 

 are crystalline, and are to be referred to the monoclinic system. 



When stannic chloride is added to quite concentrated solutions of potassium 



