BOTANICAL GAZETTE. 147 



Another obvious objection may be raised as follows : — The 

 Saprolegnice are in the main saprophytes, and yet they are said 

 to be advanced towards apogamy — parthenogenetic, at any rate. 

 The answer may be that they are saprophytic chiefly on animal 

 protoplasm, which contains more potential energy than does 

 vegetable protoplasm. At the same time, some Saprolegnice are 

 parasitic on plants, and S. ferax now appears to be parasitic on 

 fish 1 . 



I may say, in conclusion, that it was during the study of the 

 parasitic fungus of the coffee disease (Hemileia vastatrix) 2 in Cey- 

 lon that I was first led to speculate on the enormous amount of 

 energy displayed by an organism which shows not the remotest 

 satisfactory trace of sexuality, but which reproduces itself through 

 many generations exclusively by means of asexual spores. That 

 this energy of reproduction is derived from the coffee tree there 

 can be no doubt, and that it is at the cost of the reproduction of 

 the host is sadly evident; the clear inference from the fact that 

 the coffee leaf supplies substance for the reproduction, etc., of a- 

 fungus at the expense of its own fruit, is that the fungus takes 

 matters which are very rich in energy, so rich, indeed, that the 

 fungus is not necessitated to sort these substances in special re- 

 productive organs, and to secrete sexual elements, one of which 

 would then reinvigora+e the other, but may employ them forth- 

 with for the purposes of its own relatively simpler existence and 

 reproduction — Quart. Jour. Mic. Sc. , April, 1884. 



GENERAL NOTES. 



Polarity of Lettuce Leaves. — The orientation of the leaves of Lactuca 

 Scariola, which has made it one of the two best known " compass " plants, is re- 

 peated in a less degree in the leaves of the. common garden lettuce. The polar- 

 ity is scarcely apparent until the lettuce begins to throw up the flowering stem. 

 It is very weak in the curled and wrinkled varieties, but it is well marked in 

 the Cos varieties, which have flat narrow leaves much like the wild L. Scariola. 

 The observation was made on over one hundred varieties of lettuce grown the 

 present season in the garden of the New York Agricultural Experiment Sta- 

 tion. — J. C. A. 



Hibiscus Moscheutos and H. roseus. — Dr. J. Guillaud, of Bordeaux, 

 sends a pamphlet containing his investigations resulting in the identification of 



1 Prof. Huxley, 'Quart. Jour. Mic. Sc'., 1882. [It may be found upon other- 

 wise healthy salmon, according to the investigations of Mr. George Murray. 

 'Science', IV, p. 27.— Eds.] 



2 ['Quart. Jour. Mic. Sc.', Jan. 1882; noticed and figured in 'Am. Nat.', 

 July, 1882.— Eds.] 



