1879.] NATURAL SCIENCES OF PHILADELPHIA. 381 



EEPLY TO DR. M. C. COOKE'S CRITICISM OF PAPER ON "VARIABILITY 

 OF SPH.2ERIA QUERCUUM, SZ." 



BY. J. B. ELLIS. 



In the last number of Grevillia the editor of that Journal makes 

 some statements with regard to my paper on Sphaeria Quercuum, 

 published in the Proceedings of the Academy of Natural Sciences 

 of Philadelphia last March, which need correction. He says " It 

 matters not that the sporidia vary in size and form, that in some 

 (of the species) they should be obtuse, in others rather acute at 

 the extremities, in some hyaline, in others deep brown." Dr. 

 Cooke, who has examined the specimens, must have known that 

 these various forms of sporidia instead of being characteristic of 

 different species are all to be found in the same perithecium, the 

 narrow and acute forms being in fact only young or imperfect. As 

 to the sporidia being "hyaline in some and in others deep brown," 

 the record in Grevillea contradicts that statement, so far at least 

 as the species of C. and E. are concerned, Melogramma Aceris alone 

 excepted; and even in this species my specimens have the sporidia 

 hyaline. S. eriostiga is also said to have the sporidia brown and 

 biseptate; but it is added that these were free spores, the sporidia 

 actually observed in the asci being hyaline. In my previous paper 

 I stated, and subsequent observation has confirmed the statement, 

 that brown biseptate spores are found in all the different forms 

 but as j'et not in asci. They occur but sparingly it is true, but a 

 careful and patient search is sure to reveal their presence. I wish 

 here to amend my original statement so far as the color of the 

 sporidia is concerned. In all fresh specimens examined, the spo- 

 ridia are hyaline. Some specimens on Quercus alba and on Vac- 

 cinium Pennsylvanicum, both of which had been poisoned, have 

 brown sporidia, but as the color may be due to the action of the 

 poison, it will be safer to assume that the sporidia are hyaline till 

 the examination of fresh and living specimens shall show them to 

 be brown. 



It is asked why twenty other species having similar sporidia 

 were excluded from the list? Simply because I had not actually 

 examined specimens of these species, and it was not intended to 

 give mere opinion, but to state facts actually observed. As to 



