48 



JOSHUA ROSETT 



temperature differences, but the new increments of the grow- 

 ing stem are added so as to produce a bending toward the warmer 

 side of the container. Stems were grown in rectangular vessels 

 25 by 15 by 3.75 cm. The broad sides of the vessels were of 

 glass, the narrow sides of tin. In such vessels heat conduction 





'f\i 





Fig. 2, A. Microscopic appearance of beginning of annular formation. A. 

 A stem bifurcating into two horizontal branches at junction of glass slide and top 

 of solution. A', the interior of A. The glass slide upon which the specimen 

 was grown was first photographed, then the growth brushed away and the slide 

 photographed again. Magnification 24 diameters. . B. A canalicular forma- 

 tion in cross section. The lining of vertical canals of stems and openings of 

 horizontal canals only appears, the opaque parts of the growth having been brushed 

 away before being photographed. Magnification 24 diameters. 



C. Repeated canalicular formations, one above another. The lowest is al- 

 lowed to form at the surface of the solution, then more solution is poured in, a 

 second is allowed to form, etc. D. A linear figure produced by turning the glass 

 plate, to which the growth adheres, a number of times in the solution. E. The 

 effect of heat upon the stems. Actual size 25 by 15 by 3.75 cm. The broad sides 

 of the vessel ai-e made of the glass, the narrow sides, the bottom and the chim- 

 ney passing through the center are made of tin. A small flame burned in the 

 chimney while the stems were growing. F. Showing the thickening of the stem 

 below an outgrowing branch and its bending in a direction opposite to the side 

 from which the branch arises. The lining of the canals only is shown, the opaque 

 parts of the stem having been brushed away from the glass slide. Magnification 

 100 diameters. 



