Apeii, 7, 1899.] 



SCIENCE. 



509 



Debray in other plants. In fact, the phe- 

 nomena can be produced in all plants so far 

 as I have examined, whether healthy or dis- 

 eased, especially in cells containing chloro- 

 phyll. I obtained the plasmode structures 

 readily in leaves and stems of Vitis, Lilium 

 harrisii, Tobacco, Tomato, Rose and Hyacinth 

 and in Spirogyra cells. If one watches the ac- 

 tion of eau de javelle closely under the mi- 

 croscope a slight plasmolysis of the cells is 

 first seen which may increase or afterwards 

 disappear. The chloroplasts swell and be- 

 come colorless and unite with each other, 

 and usually with the rest of the pi'otein, 

 into an amorphous mass almost transpar- 

 ent. This mass after a time contracts into 

 a single vacuolate plasmodium-like struc- 

 ture or into several such structures in each 

 cell. These become highly refractive and 

 remain without much change for several 

 hours or disappear, according to the strength 

 of the reagent. In this stage the plasmodes 

 may be coagulated with alcohol or iodine 

 and stained and permanently mounted in 

 glycerine containing alcohol or iodine. If 

 dilute glycerine or pure water is added be- 

 fore coagulatiou the plasmode structures 

 swell, lose their high refraction and be- 

 come amorphous. In coagulation these 

 formations behave like any albuminoid 

 substance. Their formation, however, is 

 entirely different from the separation of 

 active albumen in the cell by the addi- 

 tion of an aqueous solution of caffeine as 

 described by Dr. Loew. This difference 

 will be discussed in a fuller paper now in 

 preparation. The action of the eau de ja- 

 velle is most likely an oxidation in the pres- 

 ence of an alkali. Changes of the kind de- 

 scribed are not produced by a mixture of 

 sodium chloride 5% and sodium hydrate 

 1 % or of either of these acting alone. A 

 phenomenon quite similar, however, is pro- 

 duced in the Lily if the tissues are first 

 soaked in peroxide of hydrogen till discol- 

 ored and sections then mounted in sodium 



chloride 5% and sodium hydrate 1%. The 

 cell contents then quickly swell and be- 

 come amorphous, and highly refractive- 

 plasmode structures separate out. These 

 gradually disappear if not coagulated with 

 iodine or alcohol. In the latter case they 

 behave as do the similar structures pro- 

 duced by the eau de javelle. If the theory 

 is correct that these changes are pro- 

 duced by an oxidation of the chloroplasts 

 and other cell contents in an alkaline me- 

 dium it explains why such structures, or a 

 reticulate form of them, usually appear in 

 cells which slowly die and become brown 

 around the punctures of aphids in the leaf 

 of the Bermuda lily. Numerous tests made 

 by the writer have shown that plants which 

 react in this manner to aphis punctures 

 contain much larger quantities of oxidizing 

 enzyme than plants which do not so react. 

 The presence of the substance injected into 

 the wound by the aphis probably causes the 

 neighboring cells to increase still more in 

 oxidizing enzj'me until the presence of the 

 latter in excessive quantity destroys or oxi- 

 dizes the chloroplasts. The cell slowly dies, 

 and the rest of the cell contents may then 

 be attacked. A brownish shrunken amor- 

 phous mass is left. On the addition of 

 dilute potassium hydrate or sodium hydrate 

 to sections from such spots the oxidized 

 protoplasm in the cells which have turned 

 brown swells up and becomes a reticulated 

 or vacuolate mass, such as is often obtained 

 with the eau de javelle or the peroxide of 

 hydrogen and sodium hydrate. It is quite 

 likely, therefore, that plasmode structures 

 would be formed by an alkali in any cells 

 that had previously become oxidized either 

 from the presence of oxidizing enzyme in 

 themselves or from any other cause. These 

 observations indicate quite decidedly that 

 the supposed Plasmodiophora vitis or 

 Pseudocommis vitis are nothing but micro- 

 chemical reactions, brought on by oxidations 

 and the influence of an alkali upon the en- 



