MICROSCOPIC INVESTIGATION. 



201 



lo«u, iu \\ liicli the .sLarcli-gTauuIes grow ; h reineseutrf .sucli a cell. These 

 cells contain from thirty to seventy granules, c represents a broken 

 cell, from which the starch is seen as if in the act of leaving ; « repre- 

 sents a portion of a broken cell ; j;, precipitated starch. The starcli- 

 granules, individnally considered, consist of the starch proper and a 

 cellulose covering or cell. 



On receiving some diseased potatoes from Mr. B. P. Ware of Swamp- 

 scott, Massachusetts, under date November 1, 1872, I commenced a 

 series of experiments on them, having in view the detection of the 

 mode of action of the fungus on the nitrogenous matter of the potato 

 and other considerations. I arranged live vessels as follows : into ISTo. 1, 

 I i)ut a strong solution of sulphate of copper ; into No. 2, a dilute solution 

 of sulphite of soda ; into No. 3, the milk of caustic lime in excess : into 

 No. 4, a very dilute solution of carbolic acid in water ; into No. 5, pure 

 "water. I placed in each solution half of a diseased potato. The follow- 

 ing will show the action and results after six days' saturation : The 

 potato in No. 1 solution was found to be perfectly preserved and deo- 

 dorized, so that it could be sliced into sections, and preserved for future 

 use. No. 2 solution failed to iDreserve, deodorize, or prevent the destruc- 

 tive action of the mycelium of fungus, contrary to expectation. No. o 

 destroyed the odor on application, l3ut iu two days the lime became 

 completely carbonated, forming a mass of chalk, when the offensive 

 odor appeared again, and decomposition of the nitrogenous cell went 

 on as if lime had not been present, and infusorial life, in the form of 

 ftactenVt, appeared in great numbers. No. 4 specimen was preserved 

 completely. In No. 5 specimen decomposition seemed to have been 

 slightly retarded at lirst, but the decomposition on the third day was 

 in full action, and the odor became very offensive before the sixth day. 

 When a portion of No. 3 was placed on a microscopic slide, and secured 

 by means of a glass disk, and viewed under a power of about 75 diame- 

 ters, masses of starch-grains appeared in cellulose cells all over the 

 jfield, as illustrated 'by b, Fig. 37. A reference to Fig. 38, F, will show 



the position of those cells, a, d, 

 t. They are held in position in 

 the potato by the nitrogenous 

 cell ty which is held in turn by 

 an outer and inner cellulose cell, 

 a, d. When a sound ijotato is 

 grated dowi;, all these cells are 

 broken, because of their perfect 

 cohesion to one another. One 

 cell cannot be broken without 

 breaking all. But in the case 

 of rotting potatoes, the nitroge- 

 nous cell which binds the three 

 together is partly removed by 

 the fungoid action, but princi- 

 pally by infusorial life (bacteria) 

 which live on it. The inner or 

 center cell containing the starch 

 is thereby liberated. This is ow- 

 ing partly to the soft and yield- 

 ing character of the cells and the machinery used in reducing the pota- 

 toes to a pulp, and being so buoyant as to lloat the starch-granules 

 within them, are carried away in the process of washing as stated. 

 Dr. Payen, as early as 184G, in a paper read by him before the Paris 



Fijr. 38. 



