130 THE AMERICAN MONTHLY [July, 



Judging from its chemical reactions, its general composition, its position 

 in the tissues of the leaf and the circumstances of its production, the assertion 

 may be made with a good degree of certainty that this ' pigment ' is an ab- 

 normal growth from the cell-contents in the outer epidermal cells, and is in- 

 duced by the action of the fungus upon this tissue of the leaf. The yellow 

 color around the black spots is due to the death of the tissues and the break- 

 ing down of their cell contents. 



Thus far all attempts to eradicate this disease, without permanently injuring 

 the I'ose plant, have been futile. Being very tenacious of life, it resists the 

 attacks of all the more common fungicides. To keep a warm dry atmosphei'e, 

 not below 70° F., about those varieties which are most easily attacked by the 

 disease, has been found a good preventative. It has been ascertained by ex- 

 periment that the fungus attacks those roses most readily which are growing 

 in very rich, damp soil. From this it is inferred that the disease maybe pre- 

 vented to some extent by placing the plants in a moderately poor soil, and 

 furnishing them with only a sufficient amount of water for growth. A Ger- 

 man writer, Sorauer, has suggested that, to prevent the spread of the disease, 

 all those leaves affected shoidd be removed and destroyed as quickly as the 

 spots appeared upon them. There is yet much to be done in the way of dis- 

 covering: a cure for this most fatal disease known to the rose. 



Notices of New Methods. — V. 



By GEORGE C. FREEBORN, M. D., 



INSTKUCTOK IN NOK.MAL HISl'OLOGY, COLLEGE OK PHYSICIANS AND SURGEONS, NEW YORK CITY. 



Alcoholic Solution of Haematoxylin. G. Cuccati.* — Dissolve 25 gms. 

 of chemically pure potassium iodide in 35 c.c. of distilled water. Pour this into 

 a bottle and add 75 c.c. of absolute alcohol, with constant agitation ; then cork 

 tightly. Grind up in a mortar 0.95 gms. of hiematoxylin crystals and 6 gms. 

 of chemically pure alum. Then add, little by little, with constant stirring, 

 the potassium iodide solution, and finally return the mixture to the bottle. 

 Allow it to stand from ten to fifteen hours, shaking occasionally. At the end 

 of this time filter through paper, taking precautions for the prevention of the 

 evaporation of the alcohol, and preserve in a well stoppered bottle. 



This solution stains with sufficient intensity, but not beyond a certain limit. 



Osmic Acid Method. A. Kolossow.f — i^n order to increase the power 

 of penetration of this reagent various acids have been combined with it. 

 Kultschitzky used formic acid. Cybulsky acetic acid, Cattaneo arsenic acid. 

 The use of these acids produce artificial changes in the tissues. In place of 

 these acids the author uses the acid salts of uranium nitrate or acetate. 



The solution recommended by him is as follows : — To a 2 or 3% solution 

 of either uranium nitrate or acetate ^% of osmic acid is added. Large ob- 

 jects [frog's lung] are divided transversely into two or three parts and placed 

 in the above solution, where they are allowed to remain, according to the 

 stain wanted, for a longer or shorter time [16, 34, 48 hours]. This solution 

 does not make the tissues brittle. 



The osmic acid stains the myelin black and the remainder of the tissues are 

 fairly well fixed. 



Gold Chloride Method. A. Kolossow.J — The objects are placed in a 

 1% solution of auric chloride for 2, 3, or more hours, until they are soaked 



* Zeitsch. f. Wiss. Mikros. v, 1888, p 55. 

 tZeitsch. f. Wiss. Mikros. v, 1888, p. 50. 

 t Zeitsch. f. Wiss. Mikros. v, 1888, p. 52. 



